I know some others have already mentioned it, but this would be a great time to move your passwords to something more secure. I recommend Bitwarden as well. You can import you current passwords fairly easily.
I'd recommend getting off saving your passwords in the browser at all and move to something along the lines of BitWarden and install the appropriate plugins to your browser.
Saved passwords in browsers are often stored in plain text. I would highly recommend a password manager like BitWarden. Makes transferring them easy and it's more secure.
I don't use separate profiles (which I reckon are analogous to accounts) - but Firefox does have a feature called 'Container tabs' where you can isolate a sessions cookies into a container (default ones are labelled things like Shopping, Personal, Work, etc).
However, I think these are somewhat moot now as I think Firefox handles cookies differently in some way that went over my head - so I'm doing that thing where I post a semi incorrect answer to ensure someone shows up with the correct one.
The containers are useful for having multiple accounts. Eg I have a work tab that has my work Gmail/PayPal/etc accounts logged in, so I can easily switch contexts without closing all my other tabs/windows
i highly recommend the official mozilla addon called 'multi-account containers'. Each container has its own cache n what not. I found it very useful for when i had to use a site both as an admin and as a regular user and didn't want to clear my cache constantly.