edc2988c548db05e33b921fed15821010bc74895 is bad, though the symptoms are different. (no output on the external monitor from plymouth; plymouth itself seems to crash and the VT is in text mode, so text input results in characters being shown in the upper lefthand corner over the plymouth background; since plymouth isn't accepting input, I'm not able to boot all the way to userspace and check whether the text VTs are accessible after X or wayland has started, since with plymouth broken the root disk does not unlock.)
edc2988c548db05 e33b921fed15821 010bc74895 is bad, though the symptoms are different. (no output on the external monitor from plymouth; plymouth itself seems to crash and the VT is in text mode, so text input results in characters being shown in the upper lefthand corner over the plymouth background; since plymouth isn't accepting input, I'm not able to boot all the way to userspace and check whether the text VTs are accessible after X or wayland has started, since with plymouth broken the root disk does not unlock.)