Why are two cells opening up when I want to type into just one in NUMBERS?

LOTS OF NEW PROBLEMS with NUMBERS as I try to create a spreadsheet for 2025 expenses. Here’s one: Tables copied from 2024. (As I did last year form 2023, and so forth.). I select a single cell into which to type text. Normally, text would wrap and the working cell and its corresponding row would increase in depth, as required. Some rows might be a little deeper than others, but text would never flow into the cell to the right, and I could always see all the info I needed in each cell. This has been the happy experience for 5+ years - up until TODAY. Suddenly, selecting a single cell results in two cells being opened: the one I want and the one below. NO WAY TO TELL WHAT I MIGHT HAVE ACCIDENTALLY DONE to make this suddenly the case - in order to reverse it. (Too many random search results have focussed on the NON-operative words in my search questions. Too much time has been spent searching “Community” hoping for a random person with the correct understanding of my problem AND a solution - And NO attitude.) I see some poor guy named Jerry had a similar-sounding problem last year and had so many people telling to him to turn on/off WRAP TEXT. NOT THE ISSUE!!!!! Questioning him WHY it’s a problem. NOT HELPFUL. NUMBERS is my tool. I have used it a certain way for years - and suddenly it is not behaving like the same tool and is making my use of it less easy and enjoyable. I’d simply like to know why or how I can remedy it. Can anyone help?

[Re-Titled by Moderator]