I've been here for, I think, about a decade.
Even when I joined, there was talk about " the good old days" and how those had passed.
For me, personally, the big change has been how aware I now am of how not mentally well /socially adept many of the posters are. I feel that when I first joined people were fairly well balanced, and the view given were representative of the people I knew IRL. But now it feels that everyone thinks that no-one should use their gardens/no one should ever knock on the door or visit unannounced/ no one child should ever knock to play/ no one should ever go upstairs in your house/no one should ever ask for a favour/ no one should own a pet etc etc, and, to be frank, normal people with normal outlooks don't feel so precious all the time. Normal, functional, people just get on with life, and shrug off minor irritations, but it seems like the MN community are rather odd, and socially dysfunctional, and think the world is out to get them.
I think that isn't MN specific though. I think that Brexit and Covid have both been big triggers for bringing mental instability to the fore, and destabilising people who formerly coped and I think that as time has moved on, the internet in general has been an escape for those who aren't mentally or socially well enough to function well IRL.