A lot of Amazon lighting I've looked at with a range of 100 - ??? is actually only rated to go to 265v and could probably work up to 277What is voltage at luminaire(s)?
if you have a bad neutral, maybe multiwire circuit or a feeder with a bad neutral you maybe not too unbalanced initially, but as more drivers fail unbalancing gets worse and impacts more drivers. The ones that see lower volts are probably fine, the ones that see higher volts is what is likely failing if this is what is going on, but that don't mean it won't change after enough fail the load balancing can be significantly different than it originally was.
285 is pretty common to see around here on what is supposed to be 277 nominal, that is only about 3% above 277 and should be acceptable.
If that's the case they might just "say" it's rated at 277 and hope the voltage isn't any higher.
That's why I asked what brand and where he bought it. I've bought a considerable amount of Amazon lighting, and I know some Chinese shenanigans