F2 (edit cell contents) also selects some or all of the text, but only in one file/workbook

Since this is only happening in a new sheet, I expect I fat-fingered some, unknown to me, setting toggle.
In all my other sheets, if I select a given cell and press F2, Calc switches to cell edit: can enter or edit cell contents, if there is pre-existing contents then cursor is placed at the end of current contents. In my problem sheet, pressing F2 switches to edit mode, but also selects all or most of the current text. Strange, I just checked every (all 6) populated cells in this new sheet. Except cell c2, all the others, pressing F2 selects all current contents. Cell C2 contains "FB, R.O. Rehabs’ and pressing F2 on it results in all but the first two characters being selected. Then after having repeatedly selected nearly every populated cell and pressing F2 to confirm what I’m reporting, the behavior suddenly stopped. It’s fixed, I guess. But I’m certain I didn’t fat-finger a fix. What happened?

I followed all applicable guidelines. Had I my research found any answers, I would not have posted at all. Had I found additional cases, I would have linked to them. If this problem is actually a feature some people consider useful, I expected someone here would know, and just say so. Troubleshoot: I did explain in detail how the problem disappeared while documenting it. If it becomes a serious recurring issue, my next step would be to install a Keylogger so that, when it happens again, I can review recent keystrokes to see IF anything I keyed was unintentional and may have triggered a toggle for this ‘feature’. For security reasons, expect it will never become that important. Reproducible: again short of having an audit-trail for Calc, we don’t know how to reproduce it. If it happens again, and I learn more, I might report back additional findings.

Guidelines for asking here:
Please name your OS. (I usually assume you use a Mac, if you don’t tell, but statistics would say you use Windows.).
Include version of OS and for Linux Distibution, deskto (gnome, kde, …) and how you installed LO (Snap, flatpack or even “was preinstalled”)
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Version of Calc you use can be important.
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If you can’t improve your question: Good luck your problem happens someone else here, who can solve it…

Version: 7.0.4.2
Build ID: 00(Build:2)
CPU threads: 8; OS: Linux 5.10; UI render: default; VCL: x11
Locale: en-US (en_US.UTF-8); UI: en-US
Debian package version: 1:7.0.4-4+deb11u9
Calc: threaded