When selecting the loader prompt, typing commands works, but the character echoed is most of the time one of /, \, | instead of the typed character.
I now tested the same with loader.efi from 13.0-RC2, and the effect is slightly different. First, I noticed a dash is also among the echoed characters, so this looks a lot like scattered remains of an "ascii spinner" mixed in.
With the newer loader.efi, instead of replacing random characters with any of [/-|\], these characters are inserted now.
For example, when I type "boot", I might get the following on loader's prompt:
I can't reproduce anything like this with FreeBSD-13.0-RC5-amd64.vhd with and without EFI.
Sorry, ignore my previous comment.