At this time the cause of this issue is well-understood and a fix has been developed. The fix is to ensure that an updated version of vala-panel-appmenu is installed on a system alongside one of the affected packages. Unfortunately vala-panel-appmenu is not part of the base install (and we don't want to make it part of the base install), so we need to identify all of the packages that are affected by this issue so we can add vala-panel-appmenu as a package dependency so vala-panel-appmenu will always be installed alongside the affected packages.
Here is the current list of packages affected, grouped by whether or not someone has tested that the updated vala-panel-appmenu is effective at resolving the issue for that package and if so whether or not vala-panel-appmenu has been added a runtime package dependency.
Package fixed by vala-panel-appmenu, runtime dependency added
Package fixed by vala-panel-appmenu, runtime dependency not yet added
- Keepassx (AKA keepassxc)
Package reported but unknown if fixed by vala-panel-appmenu
Original Bug Report
Reporting for some people in IRC as well as myself (who is also experiencing the issue). Prior to the upgrade Hexchat launched more or less instantly, now it takes 20-30 seconds before it shows up. Launching it from the command line doesn't show anything (as Hexchat appears to not have any kind of verbose logging).