I've noticed that whenever there's an upgrade, it's the Linux users who are left in the old lobby because they are unable to install the new version immediately. This is due to the way package management is done on Linux.
So for those of you on Linux who can't run the latest 0ad because it hasn't been packaged yet or won't be packaged for your OS, I have a solution that I hope works for you. It involves using the Nix package manager which in theory runs on every version of Linux and you only need to run 2 commands: one to install the package manager and one to download/compile/run 0ad.
First install the Nix package manager by running:
sh <(curl -L https://nixos.org/nix/install) --daemon
Further directions here: https://nixos.org/download/
After the package manager is installed you should be able to run:
nix run github:nixos/nixpkgs/master#zeroad
This will download and compile the latest nix packaged version of 0ad (27 as of yesterday) if it hasn't done so already, then run 0ad. Since it has to download/compile it takes some time the first time you run it; about 12 minutes the first time on my mediocre PC. But after that it opens normally.
To see what version of the code it's pulling down and compiling (as well as the build steps) you can look at this file:
https://github.com/NixOS/nixpkgs/blob/a19f7dcff880e1e6e82ea1b0f9155572b72385b2/pkgs/games/0ad/game.nix#L50
I'm curious if this works for you. Please let me know.