That's frustrating.

I assume you already tried updating using Smart Switch, right?
I made an account here just to post my solution. I know this solution didn't work for da2xff but maybe it works for others who view this thread.
My problem
I bought my Samsung Galaxy Tab S5e Wi-Fi the year it was released with Android 9 and security patch March 2019. It never received any update and always showed "your software is up to date" in the settings menu despite this not being the case. I'm unfamiliar with Odin so I didn't want to risk using it wrong.
My solution
I installed both
Samsung Smart Switch on Windows and
Samsung Smart Switch Mobile on my tablet and connected the tablet to my computer while running the software. The first time it didn't show an update button, but 30 minutes later when I opened Smart Switch a second time, it did. This was the Android 10 update, and now I'm able to download the Android 11 update in the settings menu (without Smart Switch).
Edit: don't update (17-01-2024)
If you're still on Android 9, don't bother updating. In my opinion, Android 9 is much better than Android 11.
- Android 11 is much slower. Each settings page takes at least half a second, up to a second to load. On Android 9, page loading was nearly instant. As for other apps, they take longer to load too. For example, the IMDb app splash screen needs 4 seconds on Android 11. On Android 9, it took approx. 3 seconds with cleared memory and cache.
- Android 11 has more bloatware like Bixby which I can't disable.
- App icons have become much smaller. Now, the icons are the same size as on my phone (S10e) despite my tablet having a 4x bigger screen and 2x bigger resolution.
- The PIP view interface needs to reposition itself thrice. You can't stick it to the top and bottom anymore either. And you must move it to the trash can with precision to close it as opposed to swiping it to the bottom with ease.
- The OS navigation bar swipe gesture doesn't work when an app is in full-screen mode, forcing you to swipe twice. Swiping the first time will only bring up the swipe gesture hint, at which point you need to swipe a second time.
- The overview button in Android's navigation bar (back–home–overview) swipe gesture can be cancelled in Android 9 but not in Android 11.
- Samsung One UI 3.1 frequently crashes when (specifically) viewing Youtube in PIP mode while browsing in Google Chrome. The touchscreen and buttons (power + volume) become nonresponsive for a approx. 60 seconds after which the reboots itself.
I understand this reads more like a rant than an informational edit. The reason I wrote down my complaints is for others to make a more informed decision on whether to update. For example, if none of my irritations bother you then definitely update for security purposes.
Edit 2: LineageOS (13-07-2024)
As I described in my other thread (
downgrade firmware issues), I have been meaning to downgrade my Samsung Galaxy S5e tablet but it seemed impossible. I have found
this thread on XDA and although it works for some people, I didn't manage to downgrade my tablet. So I've decided to switch to LineageOS 21 (Android 14) and doing so solved most most of my issues: better performance, no crashes, no bloatware, better PIP interface, etc.
For transparency, there are a few downsides but they are no issues.
- Bootloader is permanently unlocked.
- Samsung uses anti-consumer practices that results in denying access to certain Android/security features. For example, I cannot use my Samsung Galax EarBuds+ app for "security reasons", which is absurd because it's just a Bluetooth device interface.
- Dolby Atmos doesn't always work, but maybe this will be fixed with a future update (haven't installed the one available at the moment yet).
- Although Samsung One UI 3.1 kept crashing under certain circumstances, it does have an excellent interface and many apps and features, which LineageOS doesn't have. Sad to say, I have to resort to third party apps that often have ads and paid subscriptions.