Custom themes do not work with 115.18.0esr

[zeffdakilla]

Hi, I recently updated to a newer version of Firefox to get rid of a problem with YouTube getting stuck loading. It did work, however, any custom themes from the Firefox add-ons store do not load correctly. The solid colors do work, but any images included in the theme don't show.
It's not too big of a deal for me since the colors at least work, but I do miss my themes. Any help is appreciated.