"How do I dispute my 2021 tax refund?"
What exactly is it that you want to dispute? Do you think the refund amount on line 35a of the Form 1040 that you filed is wrong, or do you mean that the refund you received was less than the amount on line 35a?
"I used TurboTax and the new option they had last year . . ."
There were a lot of new options last year. Which specific option are you referring to? Who are "they" that had the new option?
". . . and got screwed out of $1900.00 with no explanation."
What exactly was the $1,900 that you got "screwed out of"? Was it exactly $1,900? How did you arrive at the $1,900 figure? If the IRS reduced your refund, they must have sent you a letter or notice. What does it say? If you just got the refund, you won't get the letter until two or three weeks after you got the refund. You have to wait until you get the letter to figure out what the problem is.
DoninGA and xmasbaby0 made "educated guesses" about what could have caused your refund to be reduced, but without more details it's just a guess.
"How do I get back to them?"
Who are "them" that you want to get back to? TurboTax? The IRS?
