What a mess. I have added a big warning in #1. It all started when onyx didn't release any full firmware update files anymore.
updater-script MaxLumi:10/2021-03-31_19-14_3.1_0631e26
Code:
ui_print("Patching boot image...");
show_progress(0.100000, 10);
patch_partition("EMMC:/dev/block/bootdevice/by-name/boot:12522792:436ca212b3eff288a5c71bf72fa5e5be00d0e023",
"EMMC:/dev/block/bootdevice/by-name/boot:12522792:e1380eeddffc778f949977747b8ac6db63e91821",
package_extract_file("boot.img.p")) ||
abort("E3008: Failed to apply patch to EMMC:/dev/block/bootdevice/by-name/boot:12522792:e1380eeddffc778f949977747b8ac6db63e91821");