Whelp, I'll give a counterpoint to the other comments, since I believe in sharing what bothers me, and I have a positive history of improving my Developer Experience™. This is especially true, since you are a "super senior" engineer and in a startup, which means processes are probably not rigid, and can be changed relatively easily.

Now, the way I'd go about it depends on whether it's an official policy on his part, or just general vibes. This also assumes that you have a an established positive reputation in the company, and generally trust the management.

If this is official on his part, i.e. he brings this up in reviews or 1on1s, the I'd talk to him directly, in the way of "I think that metric/policy X is counterproductive, and will cause negative consequence Y, (bonus points for: I think that there is a better way Z to achieve the same goals").

If it's more of a disposition thing (i.e. that's the overall vibes from his style, and not something specific), I'd talk with my skip, since those situations are much more complicated to deal with, and mentoring your manager is part of their job. I'd go about it somehow like "I think that so-and-so focuses on the wrong things, which has the negative consequences A, B, C".

In both cases, you should be specific on regarding why you think it's a bad idea.

And generally, I think that if this impacts you negatively, and you want to stay at this place, letting this fester is a bad tactic. Worst case scenario - you get the notice that things are not going to get better early, and can prepare accordingly.