I don’t understand why my character, with Darkvision, is receiving disadvantage attacking enemies in the dark.
Even if Darkvision was removed or changed, a blind character attacking a blind enemy would attack with a straight roll. Not disadvantage.
Removing Darkvision or reducing the effectiveness just so a few races “are less crappy” and making them all crappy is backwards thinking.
Make the races without Darkvision have something that benefits them. Human Variant is the number 1 most played race in 5e. They’re a perfect example.