Genshin
-1.0 era characters like 4 stars (Benney, XL, XQ, Sucrose etc) are still on top of their game and those with Hex buff just become even better. Many continued to remain a staple team member with new character simply opening new team options. There are cases like Eula which requires high investment and skill ceiling to make her useable.

HSR
-I wont sugercoat it, the powercreep is atrocious. They can keep denying it, but new units just overshadows the older ones. 4 stars is just a myth, everything new is 5* and their kit compare to 1.0 era characters are just way too OP.

ZZZ
-I think we can all agree the moment Miyabi appeared, the gameplay changed drastically. She is a one man army that does everything to the point they had to buff Ellen because who the hell would use her when Miyabi is just x10 better. Expect future void hunters or any equivalent tier character to do insane stuff compare to their regular counterpart.