My sm did the same thing to me. Had only been a shift for less than 4 months and with the company overall right around a year. She claimed I was being rude to a barista and saying “imagine how he felt” when I was stating that we needed to help him on warming. For context a crap ton of mobile orders came in at once and the car in the drive was waiting for egg bites for 17 mins already. I also wasn’t running the shift, my sm was. Anyways she put me on a 3 week improvement plan, and stated “if we don’t see any improvement, we’re gonna be having a different conversation”. This was about 3 weeks ago. She just fired me yesterday for “using profanity on the floor” which I never did. My advice is, get out! I missed my chance of transferring before she found some excuse to fire me.