Hopefully you'll get G.INP back soon enough. I was on interleaving (downstream) again recently, INP 3 delay 8ms, presumably because of a spike in errors. It took 20 days before DLM took positive action (restoring fastpath) and did so just after 5am yesterday. It's a shame that DLM takes incredibly longer to take positive action each time it intervenes, although I can see to some degree why it's designed that way.
From what I can see though, and what others have said, I'd also agree in that it looks like you've had a DLM reset. How though is anyone's guess. I doubt it was a backhaul change, so that leaves caution counter (perhaps?) or someone else within Openreach I guess. Strange though.