Hello!
This has happened three or four times now, quite unregurarly though, don't know what exactly triggers it.
I'm visiting Warlord and I have corruption. I walk to the quarantine array machine that cleans me from the corruption. After this I'll walk around revealing the right side of the map and notice that after 20-30 turns all the corruption comes back!
The first attached screenshot shows this happening in the log. I did check that my corruption went to 0% and it wasn't just some other robot getting scanned or something.
The next screenshot shows another game where I have 0% corruption and the second screenshot after 20 or so turns where I suddenly get 1%.
Hi Palikka! This isn't a bug. Notice how it only happens in this small part of the game. There's a mechanic behind it, but yes it's not completely apparent, more so if you haven't found the relevant lore (you may run into someone inside the base who talks about it).