I have a 2016 Chevy Suburban and it shudders when I accelerate between 30-45 mph and at time above that range.
This is a classic description of a problem with the transmission’s torque converter lockup mechanism.
I suggest that you have an independent transmission shop (NOT a chain-run joint like Lee Myles, Cottman, Mr. Transmission, or–God forbid–AAMCO) do a fluid and filter change, as well as a diagnostic. With any luck, the fluid and filter change will do the trick, but if not, they can advise what type of further work will be necessary.