PippoBaudi As of today, two issues on Google's issue tracker mentioned in the GrapheneOS issue (360767171 304994874) are still marked "Assigned", so in theory Google thinks that they are real bugs that have not been solved yet.
Or maybe they fixed it and forgot to close the issues! Recently there has been a lot of turmoil related to Android.
Wi-Fi channel numbers are a little confusing these days, but what I think we know from people who have commented on the GrapheneOS issue so far is that 5 GHz channels 38, 40, and 44 experience the disconnects, but 140 and 165 seem to work ok. Multiple people commented that 80 MHz channels work while 40 MHz channels do not. This is relevant because some people may be able to reconfigure their access points to avoid the issue -- if it's still a problem.
Might you have data to contribute on whether or not this still happens?