Nothing related to mumble disconnection would have been cause by that. Your problem seemed to be related to a race condition when connecting to the mumble server. and / or periods of high packet loss leading the mumble client and server being out of sync, leading to you being unable to speak or...
It has been implemented into canary with commit https://github.com/citizenfx/fivem/commit/8b97411420f03e7819d24ff2477cefaeefc4e13a (build 12164). The build channel you are referring to is an experiment branch, a temporary branch for testing certain features / patches before they are deployed to...
You'll have to switch to canary/unstable shortly, as otherwise shortly (in the next few days or possibly weeks) you will lose the ability to connect to any adhesive protected servers. Assuming no issues arise with the mumble fixes, you can probably expect it to be promoted to the stable client...