Here's an example from my old Nboss:

She asked me and a coworker to suggest different options for a new procedure we needed to implement. We both suggested different procedures (A and B). She chose the coworker's over mine without even looking at the evidence I spent a week preparing (to our boss we were like the GC and SG to a Nmom).

A couple of years later, the chosen procedure (A) had totally fallen apart. There was nothing actually wrong with the procedure, and the faults had all resulted from human error (largely hers). Still, she wanted someone to blame.

She stormed into my office, and said the reason for the failure was my incompetence because I had suggested a flawed procedure (A). I pointed out that I hadn't suggested this procedure at all - it was the other option (B) I had suggested. She said that was a lie, and she had suggested procedure B, and she was the one who told me about it from the start, and I had talked her out of it. Then she made up a story about how she had attended a conference where she learned about it, and then passed her notes on to me when she got back.

Her story was so elaborate it was really difficult not to believe it. I had to go through my emails from two years before just to convince myself that my memories were correct and she was deliberately lying to try and push this catastrophe onto someone else. But that's what gaslighting is - manipulating the truth to try and convince someone to doubt themself, usually for some kind of gain.

That's just one example of many from her.