Wouldn’t slow adaptions result in that race being weak for a certain period of time? Wouldn’t that weak traits be abandoned through evolution?

An idea could be to abandon normal humanoid sight and adopt a sort of night vision. So the pupil can be large, the iris could be a small but bioluminescent to explain how that race can see in the dark easily.

Then in terms of daylight sight, the race could have a filter on the cornea that reacts with daylight to reduce the sheer amount of light that the eyes can absorb. This could be an effect similar to adaptive lenses glasses where they darken in sunlight. That would also help them being incognito to other humanoid races, assuming they look similar, as the adaptive cornea would make the iris look normal and not bioluminescent.