While I do have privacy.resistfingerprinting flag on. It was my first time visiting the addon's repository page from three days ago (because I didn't know how to get this addon to actually work from earlier this year during winter.)

Some websites do work with the toolbar input when the icon automatically types into the text area and, the rest of the websites don't work with the toolbar input.

The toolbar input only works with the normal tab instead of also Firefox container tabs.

When I was finished writing from the toolbar icon and it gave me a problem sending the post by the enter key and later after that, it let me send a few posts when escaping the toolbar input without issue.

I've went to this addon options page and toggled whitelist to see If it helps with anything, nothing happens.
I've tried removing the whitelisted domain without this toggle being on (If I can remember correctly.)

When I had open my unusual social site and used the toolbar to type in things on the normal tab and it started to work like a charm. I've tested this workaround with the Switch Container addon to see If the container tab acts as a normal tab as a workaround and still does not work because it's still a container tab.

And then, I press control 1 to see If typing from the toolbar input comes back into the text area, no luck and felt like a pain to try different methods I can think of for the browser toolbar to work on any site.

I can't find any workaround that makes container tabs to act as normal tabs in order for the tab to function with the Private Keyboard extension.

I've had tested three older versions of Firefox (Dev Build) and tried the 79 version with the unusual social site and still nothing happens and used versions before 79 also, I have opened up a random website and used the toolbar input then it worked probably only with version 64. And lastly, I had used the 69th version of Firefox and opened my unusual social site and used the browser toolbar to write in the text area and unfortunately, nothing had happened.