Did you use Sync?

Try a version from Mozilla, sign into sync if you used it and see if you data is there. https://www.mozilla.org/en-US/firefox/all/#product-desktop-esr

Ubuntu may have switched to the Snap version and that version uses a different location for the profile. You can find the current location on the about:support page.

• ~/snap/firefox/common/.mozilla/firefox/

Your older profile might be under the hidden ~/.mozilla/firefox location.

You can copy certain files with Firefox closed to the current profile folder to transfer or recover personal data. Note that best is to avoid copying a full profile folder.

• bookmarks and history: places.sqlite
• favicons: favicons.sqlite
• bookmark backups: compressed .jsonlz4 JSON backups in the bookmarkbackups folder
• cookies.sqlite for the Cookies
• formhistory.sqlite for saved autocomplete Form Data
• logins.json (encrypted logins;32+) and key4.db (decryption key;58+) for Passwords saved in the Password Manager
  key3.db support ended in 73+; to use key3.db in 58-72, make sure to remove key4.db
• cert9.db (58+) for (intermediate) certificates stored in the Certificate Manager
• persdict.dat for words added to the spell checker dictionary
• permissions.sqlite for Permissions and possibly content-prefs.sqlite for other website specific data (Site Preferences)
• sessionstore.jsonlz4 for open tabs and pinned tabs (see also the sessionstore-backups folder)

I am not that up on using the terminal and the instructions didn't help me at all.

Are you using the Snap version ?

You should be able to see this on the "Help -> More Troubleshooting Information" (about:support) page.