Good lord that is glitchy looking! I tested it on Firefox and it worked okay, but loading it up on Chromium (installed on Fedora 34) I get the same as you. Works okay on both Firefox and Chromium on my Windows laptop though oddly enough... I'll need to see what can be done about that. For now I'll just make a note of the weird glitches on chromium based browsers on Linux.
Thank you for the rest of the comments.