It wouldn't matter in this case. Its usually 1 1500 line commit in a PR, or its a couple of commits but they aren't meaningful ("write large feature", "review updates", "wip", "merge branch X", etc)
Why are people writing junk commits like that? Tell them not to
Some people consider the PR the unit of work, not the commit. I don't really agree but I think its a reasonable way to do things if you are squashing the PR before merging. The problem is the size.