The user was banned. Unfortunately banning someone automatically removes all of their comments. A major flaw in the design of this platform.
Even worse: banning seems to be very un-transparent in the modlog. The fact that their comments are removed is not reflected at all. And when I search for that user in my instance's instance-wide modlog, the only thing that shows up is them being banned from three solarpunk communities for "genocide denial":
Looking on your instance's modlog is a little clearer in some ways, though it only shows 1 of those 3 community bans. There is also what looks like a site-wide ban, though it's very unclear who gave that ban. Their own instance admins? Your instance admins? Programming.dev instance admins (the admins of the community in which they were posting)? The modlog doesn't tell you.
Ok follow-up. I just checked the programming.dev modlog and it looks the same as my instance modlog. I believe that they have been banned by your instance, and the way instance admin bans works is they are banned from showing up on your instance. So I can still see their comments, users of programming.dev can still see their comments, etc. Only sh.itjust.works users can't see this user's comments, and thus only sh.itjust.works' modlog shows them as being banned.