Quick answer: SmileBASIC 4, the Switch app the ns2jb exploit starts from, has reportedly been delisted from the eShop, while early homebrew and Vulkan tests appear on Switch 2. The exploit is still userland-only.
SmileBASIC 4, the Switch 1 programming app at the center of the ns2jb Switch 2 jailbreak, has reportedly disappeared from Nintendo's eShop.
VideoCardz reports the app is gone from the North American and European eShops. The Japanese version was still available at first, but users now report it has been removed there too, while some say they can still buy it through other pages reached from the console's News section. Ars Technica says SmileBASIC 4 has been delisted worldwide, though a Japanese demo version that may work in a similar way was still available when it published. Nintendo hasn't publicly said why the app was removed or announced a patch for the exploit, according to VideoCardz.
This has happened before. Ars Technica points out that Nintendo removed the 3DS version of SmileBASIC from that eShop shortly after the smilehax exploit went public in 2016. Pulling the app stops new purchases, but VideoCardz notes it wouldn't disable copies that are already installed.
Meanwhile, early homebrew tests are showing up. VideoCardz shared footage of what appears to be a Homebrew Launcher on Switch 2, plus a clip of Vulkan running. Both outlets stress that ns2jb is still a userland exploit, not a kernel exploit, so it doesn't give full control of the hardware or permanent custom firmware. Ars Technica adds that others in the hacking scene are teasing similar exploits using other games, and that this vulnerability, which works on firmware 23.0.1, seems likely to be patched in upcoming firmware releases.