Hello together,
Unfortunately, I have also installed the update and am facing the same problem.
I’m not sure if it’s really because of TWRP or if Magisk can’t cope with the new layout… I created a new (rooted) boot.img with Magisk, copied it to my PC and then generated the MD5 and SHA256 hashes and put the file directly to “\FP3-8901.4.A.0021.0-gms-0b368514-user-fastbootimage\images\boot.img”. Together with the new hashes, I could then directly execute the update script from the zip file again. However, after the script ran without errors, the phone hangs in a boot loop…
As soon as I replace the boot.img created by Magisk with the original one and re-run the script, the phone starts normally. (But of course still without root)