Not update plugins recently.

[icymankr]

I am using Packer with nvim in one windows10 system and two ubuntu systems. The Packer in windows10 is still working for command PackerUpdate to update each plugins seems to use git. But the Packer within two ubuntu systems is not working for PackerUpdate command recently. I am comareing windows10 case and ubuntu case. In windows10 the Packer update plugins almost everyday for dozens of other plugins but ubuntu case is not working except gruvbox.nvim plugin. I checked the different gruvbox.nvim and others with in actual plugin folders under "~/.local/share/nvim/site/pack/packer/start". I did git in the folder gruvbox.nvim, I can see the git output message as below.

git pull
Already up to date.

But in other plugin folders, like as below.

git pull
You are not currently on a branch.
Please specify which branch you want to merge with.
See git-pull(1) for details.

git pull <remote> <branch>

I am not sure the cause of not woking the command PackerUpdate.

So I checked the git branch not working update plugins. The branch of working update gruvbox.nvim is "main", but the branch of not working update others is unknow like as "on git @bdb6d4a2".

What should I do?