The author didn't forget about the isekai stuff. The author just received plenty of comments like "not yet another isekai, drop this shit ffs!" and decided to listen to them.
I wouldn't be surprised if now the same people complain about the lack of isekai.
All you people who complain about not satisfying ending and lack of after story, I take it you will stop reading today and won't read any of the future extra chapters that the author may bring when she feels like it.