ML5 Learn Button inconsistent behavior

I recently purchased a second ML5 and the Learn Button acts differently from my original ML5.

When sending messages from my MC3 to my 2021 ML5 the 2021 ML5 Learn Light blinks once.
When doing the same thing with my new 2022 ML5 the Learn Light does not blink.

It doesn’t seem to cause any issues, but I’d like to understand what’s going on just in case.
If anyone has any ideas please let me know.