Had a big issue at a gig where I accidentally bumped the adjusting knob/footswitch for the tuner reference frequency. On testing, it’s actually way too easy to do, and could happen if you use the A or B footswitches to exit tuner mode.
I didn’t realise until a few songs later, the other guitarist and I kept looking at each other trying to work out what was going on. It was a sunny day so the screen was a little hard to read (with sunglasses), so it wasn’t immediately obvious that I wasn’t set to A=440Hz.
An option for a “Tuner Frequency Lock” would solve this easily, and would be relatively easy to implement.