SUMMARY This is probably still a bit in the future, but I thought I'd raise awareness about this here already. According to https://bugs.kde.org/show_bug.cgi?id=402789#c14 the crash reporting system needs modification if KDE switches from Bugzilla to GitLab.
There are currently no plans to do so. See https://community.kde.org/Get_Involved/Issue_Reporting/Why_not_GitLab_Issues.