Long checkout when using base parameter on large repo

I am testing a GH action and using the base parameter. When using the base parameter, the create pull request step starts taking 18 mins (see screenshot). I am guessing it is running a full pull (instead of a shallow one or something similar).

Steps to reproduce

Git command from logs:

/usr/bin/git -c protocol.version=2 fetch --no-tags --progress --no-recurse-submodules --force origin develop:develop