When Questie collapses and expands repeatedly while going in and out of combat, it causes the quest log overlay to stack on itself multiple times. Generally collapsing and expanding once more outside of combat fixes the visual bug.

Questie Version: 8.0.1

WoW Version: Wrath of the Lich King Classic

Bug description

Screenshots

Questie & WoW version

This should be fixed in the next update.

Closing this for now. If this pops back up after the next release, please report back @TheHulkingMango