Hi , I have filed I-140 (Downgrade Eb2 to Eb3), I-485 concurrent on Oct-2020 and got EAD/AP on nov-2021 . Yesterday I got my I-140 is approved after 20 months, Am I eligible for the portability under AC21 immediately? Do I need to wait another 180 days after today? Can my employer revoke my I140 if change the job EAD/AP even 485 is pending more than 180 days.
You dont need to as your I-485 is pending for more than 180 days now.
The new employer can take over your GC process by simply filing I-485J suppliment. Your new job should be in same or similar occupational classification and your new employer should be willing to file I-485J suppliment to prove that the green card job offer exists for you and they will be able to pay you the salary mentioned in the original PERM.
Your GC process will not be impacted even if your current employer withdraw I-140.