Komunitné fórum Firefox

I have two computers, one for personal use and one for business. Somehow the tabs between the two computers are being shared and I cannot disable it. Both browsers are signed into different Firefox accounts, Sync is turned off on both, and there are no connected devices. Yet despite that, when I go to one computer, it pops up a Firefox icon (see attached) in the taskbar that lets me open the tab open on the other computer. This is incredibly frustrating and Firefox should not automatically share this information, and should not make it so difficult to disable.

My Grandson loaded some type of coupon app and every time I log into some type of store etc. I get this coupon discount, he said it was on Mozilla Firefox. I want to delete it but I can't find it, can you help?

Firefox no longer supports Norton Identity Safe Mobile Unlock and Auto Fill UN/PW, anyone have a solution? I have Windows 10 with Norton Extensions enabled and Norton Vault is displayed but does nothing. Firefox is up to date also (that could be the problem; everything worked a week ago.)