Since Photoshop 23.4 and 23.4.1 "Margin guides" don't use the configured guide color.
to reproduce:
- open "New Guide Layout..." dialog
- make sure that "Preview" is enabled and "Columns" is not cecked
- configure "Color" to "Cyan"
- check "Margin"
Observe: the guides show up in some reddish brown but not in Cyan (this is the bug)
- now check "Columns"
Observe: all guides show up in Cyan (correct)