Opening the connections is one thing but resends and stream ordering can also cause issues since they might delay the latest information reaching the user space application even if the packet for them has actually arrived just because some earlier packet has not. There can also be issues with implementations waiting for enough data to be available before sending a packet.
If your connection is stable, the latency will more or less be the same, but TCP will consume more bandwidth because of acknowledgement packets, making it harder to keep your connection stable.
On an unstable connection, TCP latency will skyrocket as it resends packets, while UDP will just drop those packets unless the game engine has its own way of resending them. Most engines have that, but they only do it for data that is marked as "important". For example using an item is important, but the position of your character probably isn't, because it'll be updated on the next tick anyway.
I'm not an expert, but I suppose as this patch is on the kernel and not on the game, this will still improve any connection your kernel needs to do, like sending telemetry of your anti-cheat engine and other apps that make TCP requests while you are playing online games.