The creator has always said he had 4-5 seasons in mind but wasn’t sure which it would be. Sounds like he realized he had more than what season 4’s episode order was, but less than a full 5th season to go past thar, so he negotiated for an extended 4th season to end the show.
I’ll be sad to see it go, but as you say, happy that Esmail got to tell his story his way, right through to the end.