For ⪅ P1M, addons.thunderbird.net/en-GB/thunderbird/users/edit consistently returned HTTP 502s. The CF ray identifier of one of the instances of reproduction was a14f6181ab9eb2e5. I was able to bypass it by modifying, then submitting, solely one profile attribute, consecutively, rather than attempting to simultaneously modify all of them. My profile is user/roke_julian_lockhart.
For ⪅ P1M,
addons.thunderbird.net/en-GB/thunderbird/users/editconsistently returned HTTP 502s. The CF ray identifier of one of the instances of reproduction wasa14f6181ab9eb2e5. I was able to bypass it by modifying, then submitting, solely one profile attribute, consecutively, rather than attempting to simultaneously modify all of them. My profile isuser/roke_julian_lockhart.