Old NVIDIA drivers

Nvidia drivers come in standard and "LTS"-ish variants; 555 is standard, with 550 being the nearest previous LTS-ish one. The first LTS-ish Nvidia driver with Explicit Sync is 570, which (apparently) was released in Jan/Feb 2025.

Although I do feel you with the Explicit Sync support; on my workplace I have a couple of users with an Nvidia GPU running KDE Neon[a], and they all had to go back to the X11 session due to extreme flickering on Xwayland apps (particularly Chromium/Electron based). Now they're rocking the 570 driver and at least one of them (the most tech-savvy of the bunch) is running on Wayland with little grumbling.

[a]: I know, I know; despite some hairy compat issues with other Ubuntu software (wine and inkscape come to mind) all of them are happy on KDE Neon and have tolerated the warts so far.