It even happens when asking an LLM to reformat a document, or asking it to do extra research to validate information.
For example, before a recent trip to another city, I asked Gemini to prepare a list of brewery taprooms with certain information, and I discovered it had included locations that had been closed for years or had just been pop-ups. I asked it to add a link to the current hours for each taproom and remove locations that it couldn't verify were currently open, and it did this for about the first half of the list. For the last half, it made irrelevant changes to the entries and didn't remove any of the closed locations. Of course it enthusiastically reported that it had checked every location on the list.