If you are also using Facebook Container extension, when opening Facebook, an additional tab by this extension is still opened to choose container to open Facebook in, while there's already a tab with Facebook in it's special container.
There should be a configuration which contains a list of rules with domains and containers. When open a page matches some domain, only select from these containers.
But I won't have time to do this, so post here and maybe anyone interested in it.
I think it would be easier and quicker if it were possible to quickly choose a container with a key on the keyboard.
For example "Business" container could be the "B" or "1" key, "Personal" container could be the "P" or "2" key, etc... This way, when I click on a link that opened Firefox, I just had to press one key.