I’ve the same problem. Does a replacement for that GitLab instance exist anymore, even for solely the FP2? I remember being able to visit it a year ago, and Discourse isn’t a particularly competent issue tracker in the meantime, whereas ZenDesk is both private and entirely overwhelmed, (to the point of non-response to any technical report).
Even if FP had considered a FOSS OS unmaintainable, I don’t see why a tracker isn’t desirable. ZD is a private and/or more formal version of Discourse, which are both support forums. They are not issue trackers, not least due to the thread default to lock threads after a few months, which would be nonsensical on an issue tracker.