LibQTip-1.0 is not yet updated for Shadowlands, so it errors out with SetBackdrop error(s).
https://www.curseforge.com/wow/addons/libqtip-1-0

A addon author has already been contacted.

Possible Fix:
Fork to Github, fix it and use the fixed version in GSE.

Elkano told me it should be fixed now (r190). Let's go for it and trigger a new build to test it!