The same arguments I see against Kobolds and Drow from wearing sunglasses are the same ones I'd probably see preventing Kenku from being able to write on a notepad, scroll, or spellbook. Yes, certain races have disadvantages, but straight-up banning races for having any sort of disadvantage isn't going to help matters much.
What's next? Ban almost all non-Aarakocra, due to how strong flight is in 5e? Ban all non-Tortles, because you decided to run a Sword Coast game, and their aptitude at sea leaves almost every other race at a comparable disadvantage? Ban all non-human races, since Variant Humans gives you a bonus feat at level 1? Do you see where I'm getting at?
Instead of outright banning/killing kobolds, drows, etc. for finding ways to overcome racial disadvantages, and/or telling them that "sunglasses don't exist" in a world where both stained glass and functional eyewear are a thing, find other ways to challenge the party, and/or make them earn the "anti-sun glasses" in some manner.
The player could need to forge the glasses themselves. Maybe they need to spend an infusion on them, if they're an Artificer. The glasses could be a bit on the expensive side, to a low-level party. If the player gets hit, there's a chance the glasses could get damaged and/or break, so the character will need several backups, or fall prey to their racial disadvantage once more. Instead of saying "you can't," instead say "you can't, unless you..." and give them a way to work towards what they want.