Systemd-cryptsetup triggers a black screen after upgrading to 6.4.1

[Felix Rubio <felix@xxxxxxxxx>]

Using arch linux, I have had my kernel upgraded from 6.3.9 to 6.4.1. 
After regenerating the UKI, that works, I get just a black screen when 
systemd-cryptsetup should be either using the TPM to unlock the drive or 
to ask me the rescue password.

Luckily I have an old UKI with 6.3.9 (also the correspondent 
/lib/modules) so that I can boot with the old one, but the question is: 
any idea on how to debug this issue? I had the same problem previously, 
which I could trace back to the upgrade of linux-firmware and that got 
fixed two days later when the same package got updated, but now I have 
checked and there's been no update about that.

Is there any way to set systemd in verbose mode, so that I get more 
information before the black screen?

Thank you,
Felix