Ex. My 20 min average is 2:21 but now I can’t hold a 2:25 for three strokes- it’s jumper up about 20 splits

To make it worse, I have a competition this Saturday.
This. equipment issue, surely....I mean if u used to be able to hold 2:21 for 20mins even if u were exhausted from training you should be able to hold that for say 3-5mins easily. The body doesn't change rapidly*. Mentally all good? Apart from a bit of trepidation? One of the keys to overcoming race anxiety is to simply race more...accept some races will be good, some bad, most average. Make it habitual.