Not on Android (it stutters on scrolling even on newest Pixel). And I also think it's not the most safest browser on Android because Chromium is much more hardened there.
Firefox for Android does not stutter when scrolling for me on a phone much weaker than a Pixel. That suggests it's not a universal issue but something more specific to your setup.
I’ll pile on and say that it doesn’t stutter on my old and slow OnePlus Nord. Only on one weird page that was recently on the frontpage, but I guess they were simply also doing some fuckery with the scrollbar.
Source: https://grapheneos.org/usage#web-browsing