My 2023 cforce 800 xc fuel gauge is flashing when full , anyone else have this problem,  after fuel goes down it works normally again.

I have had similar issues on my 800XCs.
I would suggest looking at your connector and perhaps your sending unit.
I haven't had identical issues, but did two things.
I made sure my float arm was moving freely, because it was showing FULL always after sitting for bit while I ran a new wiring harness, though I suspect the connector was the issue.
I tweaked the pins a smidge to make sure it was making solid contact and after that it resumed normal function.