Since the latest 1.17 update the performance has decreased significantly, it is also a widespread issue, evident from reddit and I experience it myself. I estimate around 50-60 % decrease. I had around 90-100 fps in 1.16+ and now struggle to get close to 60 in 1.17 and 1.17.1. Reducing graphical settings does not change much.

Fps recorded in Vanilla Minecraft with no external mods.