The official site for the long-awaited fourth entry in the Borderlands franchise has revealed that the Nintendo Switch 2 version won’t feature the split screen mode. The split screen mode lets you play cooperatively with a friend either locally or online. Gearbox hasn’t stated why this feature is missing from the Nintendo Switch 2 version. Borderlands 4 launches on Nintendo Switch 2 on 3rd October.
Borderlands 4 on Nintendo Switch 2 won’t feature splitscreen mode

This doesn’t affect me because i don’t have any friends.
They didn’t specify why, but we all know that some things have to be cut in order for these games to run on Switch 2. Doesn’t matter to me, the most splitscreen on my Switch 2 is for Mario Kart World… so yeah…