A few times I’ve noticed that I might enter or copy data into a cell and something about that data causes the field type to automatically change.
An example: I have a text column. I type a date in that column. It changes to a date column. (I can kind of see why this might happen, but I definitely don’t want it to happen and can see no way of stopping it.)
Another example: I pasted some zip codes into a number column. That field converted to a single-select dropdown. Same thing has happened with text. (No clue why this would happen, and doesn’t happen consistently.)
The first couple of times this happened, I thought it was a fluke, but now it’s happened enough times, I think it’s a bug…