In theory it could happen but it's unlikely in practice, for multiple reasons:

- git-bug use a form of logical clock (not wall clock) that order an action in relation to other actions in the repo. Clock drifting doesn't matter.

- pushing to git usually require some access to the repo, and therefore abuse can be dealt with socially (aka you get kicked out)

What can happen for example is someone write a comment, shut down the computer and only push the next day, but in that case the comment showing up before yours is the correct merging.