Since calendar and email are in the browser I don't see an issue. But, there have been some issues with options in some Google apps that only work with Chrome.

Test and find out.

My concern is copying event info in the Linux Firefox container & pasting it either in email or calendar, both of which are outside the Linux Firefox container. I am also concerned that Firefox unpredictably freezes or flashes a black screen.

Are you on Linux now? If so, what OS and Desktop? Try downloading another copy of Firefox and run it from the folder. Do not sign into your Firefox account and see if you have the same issue.

https://www.mozilla.org/en-US/firefox/all/#product-desktop-release

I've gravitated from Apple 3c a lifetime ago, to Windows 30+ years ago, back to Apple MAC OS 20 yrs ago, to Chrome OS (Pixelbook) & Android (Pixel phone) 8-9 years ago. Current devices Pixelbook & Pixel 4XL, with a spouse hanging on to iPad pro. I enabled a Linux container & thought I'd give Firefox for Android a try before dealing with Linux container issues. Realizing I could establish my calendar and email in the Linux container, i remember all too well the problems encountered between friends on Windows collaborating with MAC programs. The devil is always in the details, with which I 'll resist boring you.

Are you on Linux now? If so, what OS and Desktop? Try downloading another copy of Firefox and run it from the folder. Do not sign into your Firefox account and see if you have the same issue. This very interesting, will try. Though I always have signed in before downloading> open download> file not compatible or some such phrase. Claude https://www.mozilla.org/en-US/firefox/all/#product-desktop-release