Comment 14 for bug 1853357

Xorg cursor artifacts all over everywhere: "When I use the evdi module and library shipped with Ubuntu in 20.04, then DisplayLink works in Xorg, but it's very glitchy, with cursor artifacts showing up constantly all over the place on all screens, both DisplayLink and non-DisplayLink."

I've seen it, it is a know issue and has a workaround: setting "PageFlip" "false" in xorg.conf. This link is not exactly about cursor issues but explains how to set the PageFlip workaround:
https://support.displaylink.com/knowledgebase/articles/1181623-displaylink-ubuntu-driver-after-recent-x-upgrades

Anyway, that is off-topic too for this issue, so if you want to discuss that, I again suggest a new report. I don't think I can help with that though.