AC21 and Employment Changes After Filing for Adjustment of Status

[AC21 and Employment Changes After Filing for Adjustment of Status]

Hi,

My AOS, EAD, AP and EB3 to EB2 downgrade were filed on 13th of Oct and so far EAD, AP and I-140 have been approved. I got a job offer from a different employer and they filed for my H1b transfer in Dec, but I did not join them and would like to wait till I complete 180 days for AC21 eligibility. My question is, since the new employer has filed for my H1b in Dec, does it count as me taking that offer though I did not join or can I still be eligible for AC21 portability after 180 days?

[Employment Changes After Filing for Adjustment of Status]

Right after filing Adjustment of Status, what happens if the applicant changes to a new employer. Does it disqualify the current AOS or does the new employer need to file for PERM meaning start from the scratch. What if the current employer is okay with the applicant moving to a new employer and would not revoke I-485. Thanks.