The DWP haven't said anything about the backlog recently, but some people are still being given extensions and some people are waiting a very long time for reviews to take place - so I think you can safely way there is still a backlog - but how big it is or what that means for individuals it is impossible to say.
BIS
Nothing on this board constitutes legal advice - always consult a professional about specific problems
Got mine a week or so ago, couldn't have come at a worse time as I'm in the middle of ESA to UC migration as well. I was given an extension automatically until 2026, but they start the review one year in advance. Just be aware of your reward dates.
