Reflection differences between 5.1 and 5.4 ?

Well, by modifying the glass material Roughness, I can got the same reflections (or near the same).

However I would be curious to understand what’s happening exactly with 5.4 and why, if someone can help?

This is the base material that was used:

By removing this and just set 0.01 to Roughness I got back the reflections.

Thanks a lot!