Magistrate Judge's omission of query about compulsion from the plea acceptance colloqouy was insufficient plain error for reversal, since, absent a claim that compliance with the rule would have resulted in a different plea, there was no effect on substantial rights, and the text of the rule deems errors that don't affect substantial rights to be harmless.
https://cdn.ca9.uscourts.gov/datastore/opinions/2021/08/17/19-10228.pdf