MacBook Pro (16-inch, 2021) Apple M1 Max Dell U3219Q macOS 12.1 Me too, I hope it's not problem from Dell monitor firmware, works with direct HDMI

Update this workaround did the trick : https://www.reddit.com/r/macsysadmin/comments/qgypzy/comment/hpjdnn9/?utm_source=share&utm_medium=web2x&context=3