Connect MacBookPro 2025 (M4) to two external monitors

Im trying to connect my macbookpro (new m4) to two external monitors.

I currently have a new studio display and an older dell (u2412m)

Studio display is thunderbolt to thunderbolt (supplied cable)

Dell is using displayPort to usb c connection - directly to the macbook. i tried to chain through the studio display but its not recognized

All three (built in, studio display and the dell are recognized in my settings) however they wont come on at the same time. If i unplug the studio display, the dell comes on just fine, but when i plug in the studio display back in, the Dell instantly goes black