I used vanilla CFW for years and one day when I went to update, somehow I accidentally installed DeepSea. It wasn't for me. Before this, my Switch launched back to the menu pretty quickly after reboots. This update changed that, making it take much longer. There a couple of other gripes so I decided to try to remove it, but I couldn't.
I went to Discord for help and a user gave me a link to an update that was supposed to help me reinstall vanilla CFW...but wound up installing a CFW from a different group. This resolved all of my issues except the long load after reboot and now I have a bright red splash screen at reboot.
I plan to just leave things as they are and be more careful next time.