You use softwares with auto "cleaning" settings like System/Registry Cleaners or Antivirus/Security Software?. it is a public computer?

It is my personal Computer. I used a registry cleaner once but a long time ago and it isn't installed on this system anymore, so no active cleaners running. As for antivirus, only the standard windows defender is active.

Edit: Before I reinstalled there was stuff inside the download history, but it was months old and newer downloads wouldn't show up after restarting firefox. I suspect its places.sqlite corrupting but why and even after clean reinstall?

You can check the current places.sqlite file

Type about:support in the address bar.

Scroll down and find the Places Database section.

Click the button Verify Integrity

After it runs, check the results. If it reports errors the file is corrupt. If not the issue might be an external factor preventing the save on exit.

the places database check doesn't throw any errors.

I'd have no idea what is causing this problem other browsers keep the history perfectly fine, firefox just doesn't want to.

Okay I found out it's specifically tinkercad.com that has problems with firefox, if i download something from within the 3d editor it will be wiped after a restart.

If I download something in the main menu, it will stay in the history after restart, IF I download something else fromt he main menu, the file I downloaded first will dissapear out of the download history and the 2nd file will stay after restart.

Edit: I have been working on a lot of 3d prints recently, and those were my main reason to check the download history, so it has been a coincidence that I used tinkercad to test the download history, and by chance I needed some software which was being kept by the download history

Okay it is an error with that specific website and firefox, downloading from the editor wont keep the downloads in the history after a restart.

Downloading from the main menu does keep it in the history but downloading another one from the main menu will kick out the old one and keep the new one. Tested it with a friend and it shows the exact same behaviour

Does the Downloads list (Ctrl+J) shows all of the saves during your session, the problem is only after restarting Firefox? I don't think Firefox should be "de-duplicating" same-named downloads either during your session or at shutdown, but maybe there is something I'm not aware of.

so im downloading the part "spacer.stl" it gets renamed to "spacer(6).stl" to prevent duplicates in the download folder if I download it another time it'll rename to "spacer(7).stl", they're both shown in the download list until I restart. Only "spacer(7).stl" is left in the list, if I now download it another time, "spacer(8).stl", number 7 and 8 will be in the downloads list until next restart where only "spacer(8).stl" is left in the list. The naming doesnt play a role, with the option to choose file location and name if I rename the last downloaded file (example.stl), after a restart only "example.stl" will be left in the downloads list. I only tested this in the same download location not two different ones.

This only applies if I download from the main menu on tinkercad, any downloads from the editor menu will be gone from the downloads list after a restart.

Edit: I tried downloading the firefox installer twice, installer(1) and installer(2) it also seems to remove installer(1) from the list after restarting firefox

Another test, even if I rename the installer by setting the option to ask where to download AND downloading to a different folder it will remove the previous installer download from the list, even without a restart

I have Firefox set to ask me where to save the file each time, so my Firefox doesn't auto-number downloads. In your scenario, it sounds like Firefox is failing to record the true path on disk of the file, so they all look the same in the download list. If you click the folder icon or right-click > Show in Folder, does Firefox select the latest save or the original (unnumbered) one?

It does select the latest save. it seems like if the download comes from the same link, firefox removes the old files in the download list after a restart

It does select the latest save. it seems like if the download comes from the same link, firefox removes the old files in the download list after a restart

Yes, I think that's right. When I check the places.sqlite database file at startup, it only has the last file name in the moz_annos table for any given URL.

During my session, Firefox doesn't update the moz_annos table, but if I go to the Troubleshooting Information page and run "Verify Integrity," then it is updated to the latest name, even while the Downloads list still shows two files. So there seems to be some anti-duplication code in the database engine that can only store the latest file name for a given URL.

Maybe it's possible to give the same-URL downloads a different URL. In theory, an extension or user script could add a unique parameter, such as a time stamp, to the URL, assuming it wouldn't break the way the page works. For example, if you are starting with:

https://www.userchrome.org/samples/Fx56_bookmark_buttons.zip

Then Firefox will treat this as a different URL:

https://www.userchrome.org/samples/Fx56_bookmark_buttons.zip?1759975305

Or if you are starting with:

https://www.jeffersonscher.com/res/servepdf.php?f=bugzilla-home.pdf

Then Firefox will treat this as a different URL:

https://www.jeffersonscher.com/res/servepdf.php?f=bugzilla-home.pdf&1759975305

So there is a possible workaround there. (That's a UNIX epoch time stamp; you could use anything.)

Alright that does seem like more trouble than it's worth, it was just easier for me to check the downloads list than going into my Downloads folder and finding the file there. Unless there is already a script or extension for it out there.

Would be cool if firefox adds an option to change the behavior to just chronologically show me my downloads regardless of possible duplications or not.

Thanks for the help.