Annoyance : merely viewing an Excel s/sheet alters some bytes

Opening a s/sheet in Excel 2019 (and all earlier versions as I recall), viewing it, then closing it, seems to result in half a dozen byte changes and so the document appears "changed", with irritating consequences for backup and other Admin activities.
The same thing does not occur with Word docs, PowerPoint ppts, .. .. as far as I can tell.
Why just Excel? Is there a way to stop it happening?
Thank you!
Excel:
Microsoft® Excel® 2019 MSO (Version 2401 Build 16.0.17231.20236) 64-bit
OS:
Edition Windows 10 Pro
Version 22H2
Installed on ‎04/‎10/‎2020
OS build 19045.4046

Hi Fergusd, I think there is something wrong with Excel 2019. In my case whenever i put something in a cell, i had to save the file, because when i put something in another cell it would delete whatever i put in the first cell. Doable, but annoying. Luckily i have access to Excel 2021 and designed the same spreadsheet again and then used 2019 to work on it. so far, no problems. do you have access to Excel 2021?

Thanks all 3 for your kind responses:
>> Try repairing the installation.
I'm really reluctant to do this (a) because in all other respects Excel works just fine; (b) because the same glitch has occurred on all previous versions (2007, 2010, 2013); and on several machines; and with several OS (XP and 7 as well as 10).
>> Neither of mine changed at all merely by opening & closing the file.
Interesting. I've just experimented again. I did not even move the cursor within the file (as one might actually do in a real-life review or search). As you did, I opened it and immediately closed it. The file size and for that matter the file timestamp are unaltered. But: a comparison of bytes gives
$ cmp -bl CURRENT PREVIOUS
1133 140 ` 340 M-`
1134 251 M-) 51 )
1135 60 0 326 M-V
1136 2 ^B 110 H
1137 306 M-F 5 ^E
1138 147 g 144 d
and the fact of the change shows up, indicating the requirement for a new backup procedure. (When you say "Nothing of mine changed at all" do you include a byte check?)
>> I think there is something wrong with Excel 2019.
Oo-er! I don't get any freakish behaviour like this - as commented above, my copy of Excel 2019 works perfectly well in all respects other than that which is the current topic.
Just to repeat - I don't get so much as a byte change when reviewing a Word doc or a PowerPoint ppt. Very weird.
Thanks anyway!

Does this happen with all excel files, or only some? I have a few that insist on asking me to save on close, and I have given up trying to find out why. Possible causes are:
* any vba code
* volatile functions
* floating charts (this is just a suspicion of mine)

I usually just save, because I can't always remember if I actually changed anything!

Berton said:

What I have seen with Excel and other spreadsheet programs is that merely widening a column to see all the characters in it makes a change and am prompted to save when closing the file or program.

That, I would have expected. The shape / structure of a s/sheet is surely as fundamental a component of its architecture as its content; similarly, merely altering the Layout of a Word doc would trigger a prompt to save it when closing .. ..