For anyone still struggling to get this installation working via snap and looking for a workaround the latest version of this can be downloaded from the following link and likely built for Arch/Manjaro using Debtap (haven’t tested yet): https://updates.signal.org/desktop/apt/pool/main/s/signal-desktop/signal-desktop_1.39.4_amd64.deb
Otherwise the latest version of Signal (1.39.4) can be downloaded from the testing or unstable branches of the Manjaro repositories using the following commands:
sudo pacman-mirrors --api --set-branch testing # change branch to testing or unstable sudo pacman-mirrors --fasttrack 5 && sudo pacman -Syyu # rebuild mirror list + update packages sudo pacman -S signal-desktop # install signal-desktop package from testing branch
Below is a link for more information:
https://wiki.manjaro.org/index.php?title=Switching_Branches
Despite these being effective workarounds I would still very much like to know what the issue with snap is 