"The Saviour" unique sword support gems not working properly

Supports modifying the damage of the Reflection skill have never done anything, because the Reflection skill never deals damage - it just summons a Mirage Saviour which uses a different skill. Those supports need to be on the skill that you triggered Reflection with, since that's the skill the Mirage Saviour uses.

This has always worked this way.

It did not work that way in metamorph league and has never done so. As one of the people who made the skill, I can assure you you are incorrect. The interactions you are suggesting fundamentally do not make sense with how skills work in PoE - I don't think we could make it work that way if we tried.

The skill was tested thoroughly and the behaviour you are suggesting would definitely have been found and raised as a massive bug, because for that to happen, the skill system would need to be fundamentally broken. I tested it myself at the time and it definitely worked correctly back then, just like it does now.

Reviewing the code history also shows no functional changes to the skill code, other than the restriction that was added to prevent the Mirage Saviours being able to have extra strike targets and a fix for an instance crash in certain cases of destroying them.