By downgrading plymouth from 23.360.11-0ubuntu2 to 22.02.122-4ubuntu2 by hand, the passphrase worked so it's a plymouth issue rather than cryptsetup, it seems.
https://launchpad.net/ubuntu/+source/plymouth/22.02.122-4ubuntu2/+build/27587072/+files/libplymouth5_22.02.122-4ubuntu2_amd64.deb https://launchpad.net/ubuntu/+source/plymouth/22.02.122-4ubuntu2/+build/27587072/+files/plymouth_22.02.122-4ubuntu2_amd64.deb https://launchpad.net/ubuntu/+source/plymouth/22.02.122-4ubuntu2/+build/27587072/+files/plymouth-label_22.02.122-4ubuntu2_amd64.deb https://launchpad.net/ubuntu/+source/plymouth/22.02.122-4ubuntu2/+build/27587072/+files/plymouth-theme-spinner_22.02.122-4ubuntu2_amd64.deb https://launchpad.net/ubuntu/+source/plymouth/22.02.122-4ubuntu2/+build/27587072/+files/plymouth-theme-ubuntu-text_22.02.122-4ubuntu2_amd64.deb
By downgrading plymouth from 23.360.11-0ubuntu2 to 22.02.122-4ubuntu2 by hand, the passphrase worked so it's a plymouth issue rather than cryptsetup, it seems.
https:/ /launchpad. net/ubuntu/ +source/ plymouth/ 22.02.122- 4ubuntu2/ +build/ 27587072/ +files/ libplymouth5_ 22.02.122- 4ubuntu2_ amd64.deb /launchpad. net/ubuntu/ +source/ plymouth/ 22.02.122- 4ubuntu2/ +build/ 27587072/ +files/ plymouth_ 22.02.122- 4ubuntu2_ amd64.deb /launchpad. net/ubuntu/ +source/ plymouth/ 22.02.122- 4ubuntu2/ +build/ 27587072/ +files/ plymouth- label_22. 02.122- 4ubuntu2_ amd64.deb /launchpad. net/ubuntu/ +source/ plymouth/ 22.02.122- 4ubuntu2/ +build/ 27587072/ +files/ plymouth- theme-spinner_ 22.02.122- 4ubuntu2_ amd64.deb /launchpad. net/ubuntu/ +source/ plymouth/ 22.02.122- 4ubuntu2/ +build/ 27587072/ +files/ plymouth- theme-ubuntu- text_22. 02.122- 4ubuntu2_ amd64.deb
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