What is an RIF?
That's how tech companies usually do layoffs. Rather than admit they overexpanded and have to cut people (or that they are cannibalizing their own people to boost executive compensation) they blame it on departing workers by increasing the PIP-rape cutoff.
Basically a company's last effort to cover their butts before firing you. If you contest the termination, they can claim they gave you fair warning and a chance to improve.
If you're ever on one, the sensible course of action is to look for another job. You're next on the chopping block.