Those were never subforums, but something called prefixes. You can still browse that way, by clicking on a 3D prefix. For example, this link will show you the same thing: https://www.hometheaterforum.com/community/forums/blu-ray-and-uhd.88/?prefix_id=10
It's probably more a fact that a bug was fixed. You probably uploaded it some time in the past before this permission was in effect. Animated avatars are limited to folks who are Supporters or Patrons:
The site is actually faster by every metric (nearly 30%). The first thing I'd suggest doing is clearing your browser cache. If you can give any specific links/screenshots or examples for me to look at, that would be helpful.
The goal with this upgrade was to get us to the latest version of XenForo, which brings some meaningful improvements under the hood, in addition to some nice features for you.
To get a summary of what is new in XenForo 2.2, see below.