If younger teachers grade easier it think it is for the same reason. They just are not sure where that line is between too hard and too easy and they don’t want to ere on the hard side.

Younger teachers might just remember a little better what it was like to be in school and they don’t want you to hate it.

Younger teachers feel closer to you emotionally, so their thinking is closer to that of a peer than an older teacher who is more of a mentor.

Younger teachers might be a little insecure and need you to like them, so they’re less critical; as they get older, they feel less of a need for approval from their students, so they get tougher.

Any or all of the above and more are probably at play in any given teacher at any given time.

At the same time, I was also more willing to hear excuses. So deadlines could get extended, things could get shifted around easily.

After a few years, I have heard and seen it all… and I also had more realistic expectations for what my students could produce.