See, gh is installed in WSL, with gh auth setup-git done.
But in dev container there is no gh installed, let alone gh auth setup-git

So after 1st push, no other push happen unless I restart container. The error being unable to authenticate with GitHub.

But today by some miracle 2nd push happened, else I would have attached a screenshot now.

Still, if you wish to investigate here are my 2 repositories where I found this issue happening:
Repo 1 (use rewrite-sapphire branch)
Repo 2

If I get an error while pushing, I'll make sure to take a screenshot of error & grab logs

Alright. I guess I don't understand devcontainers very well but I thought that a devcontainer was isolated from the rest of your system so I don't really know what gh has to do with this at all. Like, why would you expect a push to succeed or not in your devcontainer to be related to gh at all? I would have thought that authentication on your machine would be totally separate from inside the devcontainer?

Sorry for the late reply (I was busy in IRL matters).

So, here's the stuff from vscode - https://code.visualstudio.com/remote/advancedcontainers/sharing-git-credentials

Basically, dev containers share credentials from host. Now it so happens that during my experience, 2nd push also worked, sometimes it did not. When it didn't, the log messages said authentication error.
Since the credentials were set by gh auth setup-git on host (i.e. WSL), and were used in dev container (by some arrangement of vscode), git push via vscode git menu didn't work couple of times after 1st successful push.
Thus I searched online for solutions & similar stuff, but found nothing and resorted to asking here in gh cli discussion

I documented my problem here - https://github.com/orgs/devcontainers/discussions/88

I feel this is more relevant to VS Code devcontainer than gh CLI

Once this strange issue of mine is resolved on that discussion, I'll mark current discussion as solved by referencing the solution.

Thanks for the update, hope you get it resolved 🤞