'''System Information''' * Firefox: version 86.0 * Hardware: Dell XPS 13 9370 * OS: Manjaro Linux x86_64 * DE: XFCE * CPU: Intel i7-8550U (8) @ 4.000GHz * GPU: Intel UHD Graphics 620 * RAM: 16GB * Multi-account containers: 7.3.0 * I use Pihole hosted on an RPi. '''Problem''' For the last few versions, opening Firefox would result in no pages loading. The tabs would keep spinning with no result. I've disabled plugins to find the cause, and have found that I can't reproduce this issue with no plugins enabled, but can reproduce this issue with ''only'' the Firefox Multi-account containers plugin enabled. This problem also doesn't happen if I delete ''rm -rf ~/.cache/mozilla/firefox/*.default-release'' before starting Firefox, even with the plugin enabled. When I have this problem, I can disable the Firefox Multi-account containers plugin to get the tabs to load, and then re-enable it. This implies the plugin is somehow blocking the tabs from loading. Thank you for taking the time to read this question. Let me know if you would like any more information.