Works as intended. I can now contain spying websites on their own sandbox and use M365 on multiple accounts simultaneously.

Simply awesome

Can someone explain to me what's the difference of Multi-Account Containers with the new site isolation feature in Firefox? Is it still useful to have the multi-account containers?

Such a useful extension. I'm a freelancer who works part time for four different companies, all of which have onedrive and sharepoint sites plus other systems. Being able to simply open onedrive/sharepoint etc in the 'company 1' tab then the 'company 2' tab and have it log me in to the right place automatically without hassle is a massive time saver and so useful. Love this extension.

Awesome to separate your buying from banking etc.