How common is it to crash after a long remission?

Crashed in 2023. First year was hell, second purgatory, third year was generally really good, only now, seemingly out of nowhere, I’m having a big crash in way which hasn’t happened in a long time.

I don’t think my diet changed, nor am I unusually stressed, and everything else is basically the same.

Hoping to heal again. Is it likely given the mostly upward trajectory?

Five years out now and I still experience periodic crashes, but I have not gone four months yet without one, so maybe different scenario. Based on my experience I would say your outlook has good odds.