One of my iPads automatically updated to the latest iOS yesterday (15.3) and the Plex App has stopped working. It basically just freezes trying to display home page of my server. It’s working fine on other iPads and on my Roku boxes. Running the latest 1.25.5.5492 on a Mac Mini
(I have a lifetime pass)
On my iPad, I was able to fix my app by unpinning all other libraries (top left hamburger → Edit → tap all the irrelevant/grey-named orange pins). You do have to wait for the app to load to do this though. There were ~20 libraries pinned I could not see and was not using.