New job after i140 approval

Hello Experts,
My i140 was approved in Dec 2022 and I have a valid H1B VISA till Dec 2025. My question is with regards to the process I need to follow if I switch to a new employer. If I work for a new employer, I am assuming that I would need to undergo the process for PERM again but my priority date would remain the same.

In the above case, do I need to make sure that my new employer complete the paper work for PERM before the validity of my current H1 VISA (which is Dec 2025)? Also, since in the above case my H1 need to be transferred to the new employer, would USCIS increase my validity date further beyond Dec 2025?

Thank you and appreciate your responses.

Thanks, and Regards