The best experimental research we have on post scarcity society began with the Mouse Eutopia experiments. When a mouse population becomes post scarcity, it grows out of control and then thier psychology alters over several generations in a way that causes a population implosion. You see a break down in social norms that leads to a wide spread of sociopathic behavior and reduced reproductive drive. When a mouse population hits this point it triggers negative population growth where refusal to procreate/increased homosexuality, decreased care for offspring, increased murder rates, etc cause population decline despite the infinite resources. If scarcity is not reintroduced, the mouse population will completely die out within just a few generations.
Not only has it been theorized that humans will do the same thing, but it seems we are already doing it to a degree. Many of the world's richest nations are currently experiencing lesser manifestations of Behavioral Sink and have a shrinking population whereas nations where people have to struggle to get enough resources have rapidly growing populations.
Post scarcity can overwhelm the psyche in several ways that lead to behavioral sink.
The primary explanation given by Calhoun in the Mouse Eutopia experiments for the breakdown of society is social addiction. With unlimited resources, populations grow out of control until overcrowding makes social isolation virtually impossible. This means that all interactions (eating, drinking, bathing, sex, etc.) become conditioned as social activities. So, no matter how much space you eventually give the population, they will choose to overcrowd themselves which leads to elevated stress which leads to increased violent and objectional behavior.
That said, we do see this problem happen in modern society where overcrowded schools systems and social media make socialization impossible to escape. Large cities like New York draw in millions of residents to horrible living conditions with the promise of constant and inescapable social stimulation. While your government might provide 5000sqft of living space, your population will quickly grow to the point where the only way to offer this much space is to stack these homes into massive hive cities. So, while your home may be big, you don't need a job so you're average day will consist of leaving and attending back to back simulating events outside of your home; so, you will experience overcrowding the same way that Calhoun's rats did in his latter experiments regardless of having a private place to call your own.
While Calhoun's follow up experiments proved that this was only a minor factor in behavioral sink, creating more places where privacy can be observed did not prevent the phenomenon from happening, only reduced it a bit.
Follow up research in humans like the Baum study on College dormitory layouts and various case studies into the bystander effect also show a degree of correlation between overcrowding with psychological unwellness and moral decay, but again, this research alone does not produce the pronounced levels of variance seen in Calhoun's early experiments further demonstrating that behavioral sink is only in part controlled by overcrowding.
A second issue with post scarcity is a total addition to oneself. While some of the rats in Calhoun's experiment became obsessed with thier gangs. Others formed groups addicted to self care. Other experiments have show that even without overcrowding, rats giving unlimited access to food, water, toys, and drugs will often pick a vice and overdose on it.
That said, a rat living in a small group with unlimited resources will generally do well, because the social interaction becomes the scarce thing that they aspire towards. So IF your post scarcity society could somehow produce a healthy scarcity (but not total lack of) social interaction, then your people should do much better. But the only way to achieve this with a large population is by basically locking everyone up in small communities; otherwise, human nature will draw them into social addiction issues.
This is the worst part of behavior sink that often gets overlooked, and the most likely X factor that Calhoun failed to account for in his experiments. It is the nature of humans (and many other animals) to want that which can not be easily had. In a scarcity based society, this typically means things like food, water, shelter, safety, etc. We are hardwired to dream about and pursue fringe desires or else our ancestors would have never survived. However, as basic material needs become trivial we become desensitized to caring about them so we move on to want more luxurious needs met like cars, iPhones, air friers, etc.
This is the premise of Maslow's Hierarchy of needs, but Maslow was overly optimistic in what he thinks the top of the pyramid looks like, since actual people who get past the 1st 4 layers rarely care about self-actualization. When you look at people like kings and emperors, they don't care at all about being thier best selves, they are goal addicted just like the rest of us but they will make up new goals to keep themselves entertained. These people will rape a man's wife in front of him, he will steal an Olympic Champion's gold metal out of thier hand, he will have his whole family put to death... not because he needs these thing to self-actualize, but because it takes these extreme behaviors to even begin to touch on what is "out of reach" for people this unaffected by scarcity.
The problem with true post-scarcity is that you no longer want for material things, and you have more than enough time to spare to fulfil all of your social needs meaning that like an emperor, anything you can do within the rules of your society is something you can take for granted. But the same psychological mechanism that leads a poor man to fantasize about a hearty meal, or a middle class man about his dream car that he has to work hard or take a risk to get leads a post-scarcity man to fantasize about some other type of thing that he'd have to work hard or take a risk to get. Whatever society says no one (or only the privileged few) are allowed to have, such people desire, which leads to a pattern of behaviors focused on violating laws and social norms. Things like murder, rape, incest, theft, arson, reckless driving, etc. become the daydreams of a man who can have and experience anything else he desires when that is all that is left just out of reach.
If humanity hits true post scarcity, it could easily trigger the worst in us as our focus goes from building healthy relationships to help us overcome scarcity to sadistic desires... only instead of it just being the a fraction of the top 1 percent of people, it is now everyone acting that way.
The Good news is that your setup is not actually post scarcity
The term Post Scarcity is often used to describe a society as explained by Carl Marx as allowing "the general reduction of the necessary labor of society to a minimum, which then corresponds to the artistic, scientific etc. development of the individuals in the time set free, and with the means created, for all of them." However, even Carl Marx admits that some scarcity still exists in his idea of an ideal socialist state; thus, he never actually claimed that socialism would lead to post scarcity.
Actual post scarcity means that you have at demand whatever resources you want which is why many people claim there is no such thing, just various levels of automation. The limits on your personal development stipend, lack of ubiquitous personal transportation, limited medical access, and limited education caps are all scarcities that people will still want to work to get better than.
At this level of socialism, you will certainly see some elements of Behavioral Sink kick in, but it should not turn into a total hellscape like Rat Eutopia since there would still be a fair amount of actual scarcity to strive to overcome.