FYI... Firefox Sync IS NOT A DATA BACKUP SERVICE https://support.mozilla.org/en-US/kb/how-do-i-set-sync-my-computer https://support.mozilla.org/en-US/kb/how-do-i-choose-what-information-sync-firefox https://www.mozilla.org/en-US/firefox/features/sync/ https://hacks.mozilla.org/2018/11/firefox-sync-privacy/ Sync is not a backup tool but it is a good sync/transfer/move tool https://support.mozilla.org/en-US/forums/contributors/707681A

But whenever I reinstalled windows and re-signed in to firefox before it saved all my history and stuff. What happened this time?

Sorry, but if your data is not on another device, there is nothing we can do. I blame Mozilla for not making more of an effort to repeatedly warn users that Sync is not a backup service. That's why my data is in more than one version of Firefox and on multiple devices. see old screenshot

Sync Firefox data https://support.mozilla.org/en-US/kb/sync

So there is no way I can get any of that back? I had a lot of important passwords and information on that browser and since it synced before I just assumed it would work this time.

Unfortunately no.