If gravity were to be gradually reduce by 7%, over the course or weeks of months, would an average human be likely to notice? Specifically the reduction in weight, not atmospheric changes or other consequences. Like one day, after the weeks of it changing, you roll out of bed and notice "hm, I feel lighter" or you notice that there is more bounce in your steps.
It would be noticed way before you got to even 1%.
A lot of stuff humanity does depends on very high precision measurements of mass. Chemical and pharmaceutical industries would have their factory lines failing when you need to get X micrograms sample of something from a source weighting a ton and all of a sudden that sample has a density different than it was before.
Also notice that reducing Earth's gravity by any amount will cause all satellites to increase the mean radius of their orbits. A slight change in a single GPS satellite would cause its signal to be wrong and the satellite to be marked as unhealthy (thus being ignored by all devices). A slight change in all of GPS constellation at once? Nothing depending on GPS would work, and people would want answers ASAP!
Yes, if it happens quick enough. We rely strongly on our instinctive understanding of gravity and how it works. Everything about how we move including our gait is perfectly tuned to Earth's gravity. Every movement would feel wrong, people would notice that they couldn't throw objects properly anymore, and dropped items would fall noticeably slower. Pro and amateur athletes around the world would completely freak out and people who regularly lift heavy things for work (eg construction) can tell the difference when a bag of cement which is standardized to always weigh the same suddenly is easier to lift.