As mentioned previously, I believe the last version that worked fine was the one released in August 2021 with Kodi 19. For me it broke some time before the November 2021 update when I had to switch over to the dev packages for an unrelated issue. Judging by my browser history, I think I applied the unrelated dev fix around 2021/10/16, which is around the time when I started noticing the flickering artifacts.
I have tried a fresh install with the Nov 2021 release but it didn’t make a difference.