Some clarification may be needed. Mobius offer 2 ways to change "intensity" (Point and Schedule). I'm assuming you're referring to schedule intensity when you say 75% (if I'm wrong please correct me).
We can approach this 2 different ways.
1st we assume that the G5s are performing correctly and what you're experiencing is unintended charging of the point and/or schedule intensity, or acclimation mode was enabled unknowingly.
It should be easy to determine if point or schedule intensity was changed by verifying your settings in mobius.
Acclimation mode is harder to rule out because what you described seems to be on par with what you'd experience with acclimation. Lower par one day and higher par the next day until it reached the preset schedule intensity.
Here's a scenario that fits, assuming that this was unintentional acclimation. When you tested par at 75% schedule intensity with acclimation enabled and set to 65% (for example) it would've given you a par value for 65% instead of what you thought was 75%. And when acclimation mode ran its course you tested par again and unexplainably got a higher value. What makes this so hard to rule out is after acclimation is complete there's no record of it.
2nd scenario, is that what your experiencing is some sort of bug within the software. And if that's the case the only thing you can do is reach out to ecotech by either reporting it through the mobius app (shaking it) or contact them directly.
A feather in your cap might be to ensure acclimation is disabled set the schedule intensity to 75% and see what the par levels are, if they are still within 450-580 then slide the schedule intensity down until you see 360-460. And use some deductive reasoning to determine whether it's a bug or not.
It's highly doubtful that they intentionally pushed an update to make the lights work better. That would be so detrimental to so many reefs.
