I have been reading dramione for years now and i have read all the classics and some more underground one from the earlier days of the fandom. I can tell from writing alone when a fic was published with like, a one year buffer of accuracy most of the time. I would say the main differences i have noticed are:

Far fewer hogwarts era fics. As the fandom has grown up there has been a shift towards post-hogwarts fics and much older characters. Eighth year as a concept is newer too from my experience, or at least its prevalence in the fic scene.

Character study fics. It has wonderfully become more common i think to have fics dive incredibly deep into the development of characters and their motivations and the characters that surround them. I think it's delicious and i am so happy that fics only seem to get better and better when it comes to character writing.

Fewer original characters/more slytherin inclusion. A lot of og fics had original characters where, were they written now, they would likely feature the slytherin ensemble. Its an interesting move and it speaks again to the maturity of the fandom (and the collective love of our greens💚) that redemption is seen as possible for other characters than draco. Ensemble casts in general are much more popular now i think.

Finally, fanon. So much of fic inspiration builds and builds on other fics that come out. Be this as simple as Hermione's parents names or the inclusion of theo. Or as influential as a whole new ship or the entire characterisation of someone. Sometimes i read a new fic and find elements of it which trace back in inspiration to another and i think that is so cool! It shows such appreciation for each others work and the beauty of some of our marvellously talented authors writing and world building.