In 1.4.21 basic flotilla shiled was buffed, but quest shield was not. Now it is a lot worse then basic shield, though icon implies it should be reverse.

In short, buff quest modules too when you change balance.

Could be intentional, quite a few of reward mods are simply trash meant to be there if you do not have the tech yet.
But judging from your experience suggesting it might have been better pre-buff, you may have a point.

1.5.3 changelog mentions it is fixed now, I'll check it.

Nope, not fixed :(

I'll notify the team that this one slipped through the cracks (again).