I've noticed that Google Chrome has a very subtle lens flare effect for inactive tabs. Just hover over a non-active tab and look very closely at the mouse pointer. Also Microsoft's new Fluent Design introduced something similar (Fluent Reveal Effect).
Here is an example for what I mean, also the lens is a bit too bright in this case: https://i.imgur.com/6dQ6iOS.gif
In my opinion it can help to mitigate a boring grayish hover, but the effect must be very subtle, so the user doesn't notice.
Great design resource
100 Things Every Designer Needs to Know About People (Voices That Matter)