User blog comment:MisterWoodhouse/Blogs are now available on the Unified Community Platform/@comment-35944674-20200820125314/@comment-26339491-20200820225256

It so sounds like your wiki's theme may have been changed or reset. Without a link to your wiki, it's hard to figure out exactly what happened, though. Same with the audio issue. It could be that there is a but, or it could be that you were using an extension that's not currently available on the UCP.

The issue with galleries is known and should hopefully get fixed soon!