I confirm this issue. It affects plymouth in general, not related to any passphrase entry.Booting in recovery mode helps to get around the plymouth problem, but if there is not enough entropy gdm3 will simply not start. Pressing keys/switching VTs leads to the crng_init finished message to be printed and gdm3 starts after that.
Please consider adjusting the importance of the issue, it makes the system almost unbootable for regular users.
