Extended Support Releases do still include the flag: https://support.mozilla.org/en-US/kb/add-on-signing-in-firefox#w_what-are-my-options-if-i-want-to-use-an-un

Extended Support Releases do still include the flag: https://support.mozilla.org/en-US/kb/add-on-signing-in-firefox#w_what-are-my-options-if-i-want-to-use-an-unsigned-add-on-advanced-users https://support.mozilla.org/en-US/kb/add-on-signing-in-firef...