Actually, what happened next was no boot at all. It reported the partition was corrupted and suggested I run fdisk which I did and completely wiped out the partition which had Xubuntu 24.04.1 on it. I can still boot successfully into debian bookwarm 12.7 and BunsenLabs boron (debian 12.7)
I still have plenty of space on the system which I was using as a test bed for different debian-based distributions.
In conclusion, the isssue was not corrected, it was eliminated.
Thanks to @halogen2, @rubi1200, and @ajgreeny for the suggestions.