I don't know whether it qualifies as very strict, but their content policy does prohibit it:

Do not submit content depicting a child (both real and virtual) engaged or involved in explicit sexual activities. A child is defined as a person who is under 18 years old; or a person, regardless of age, who is presented, depicted or portrayed as under 18 years old.

I'm not aware of any enforcement issues, though I only follow their animemes, anime_irl, and meta communities. And of course, dessalines didn't cite anything specific, just said “No, that is full of CSAM” and locked the thread.