I’ve been running the 4.1.1 and have been since just before this all started. I have to suspect there is a correlation, but I don’t know that for sure.
To see what’s going on, you can go to https://www.quincyallen.com and look at the books widget on the home page. Keep refreshing to view the multiple covers.
You will notice that “The Best of Penny Dread Tales” book cover renders normally and “The Resurrection of Samhain” cover renders cropped top and bottom as does “Out Through the Attic.” The latter two covers were added to the WFP site after 4.1.1 and the addition of the Book Table Add-In. The Best Of cover was added before those.
It almost looks like it’s cropping to a default square, as if it were an album cover, but that’s just a guess.
I’ve tried a number of different things to resolve this but have had no luck.