CP has a point. It's usually just image posts that aren't signed with "Q".
I know this doesn’t help, cause I don’t remember who or the actual rules, but...
I went down this road a couple of months ago and an “anon” that is on the Q-Anon thread set me straight.
What I seem to recall is:
“Q” doesn’t sign photos only or a repeat drop with no further dialogue.
Not sure why 4621 wasn’t signed. It doesn’t seem to fit any pattern.
mayabe it’s unique to whichever “Q” is doing the drop.