What makes you think they did know? Look at these covers, most of them are fairly basic. Your average shitlord could have designed all of them in an afternoon and had enough time to make a few Let's go Brandon memes besides.

They may have scrambled to make new covers and do a "find and replace" on the manuscripts before going to print, but once you have everything else ready to go, that's child's play.

Printing could take a few weeks, which coincidentally omicron's been out for a couple, but if you publish once you have a few thousand copies, you can just blame shortages and distribution issues for any delays once you run out of what you already have printed.