I commented on the post, as I am running an M2 Mac Studio on Sequoia 15.0.1 and Blackmagic Design Desktop Video 14.2.1 with my UltraStudio 4K and it runs just fine. And I didn’t have to try the terminal hack, it just worked. And I tested it in Adobe Premiere Pro 14.6.3 and it works just as it should. So it isn’t the Thunderbolt 2 adapter not working with a driver, or the latest driver fixed it.
I am so glad it still works too, as I am busy parenting and with a newborn unable to work right now, so I wouldn’t have been unable to replace it for a while.