I believe when the beta period ends the beta forums are closed.
You might have wrong expectations regarding the beta forum and this forum. While there are some Garmin employees around and sometimes helpful, the information throughput between those forums and Garmin seems rather low and almost non-existent for the Garmin to forum participants direction. Issues do not seem consistently prioritized per the number of complaints. Some big issues are fixed after a long time, but it's unpredictable. Still, your best bet is probably to make the issue visible and get some Garmin employees or forum members with "connections" file an internal ticket for you. Then hope that starts align so that someone capable gets some cycles to work on it. But don't hold your breath.
But it can't be the case that every department works so differently. You can always write in the Epix Beta Forum and the status is changed there when you open a case.
In the Edge Forum there is no status change of the tickets, as soon as a beta goes public everything is blocked, although errors occur in the final release, such as the massive battery problem in 19.19, where there is no reaction from Garmin
My Forerunner 965 17.21 (beta) is non-responsive with a black screen after every reboot. I need to connect it to a computer or enter the emergency screen to unbrick it after every restart (or crash). Many other beta users experienced and reported the same. It's beta, so I'm not complaining until it's truly bricked. But Garmin struggles fixing it for a couple of updates now. So I am not sure if this depends on the department.
