I have been saying that there is a glitch in the system and that same thing happened to me. I have one or two cases where the person was 22 or 23 and a dependent in 2019 and have moved out for 2020 filing independently and PS calculated the stimulus for them in 2020. I realized that when PS transfer the personal information from 19 to 20 and we erased the dependents, that blank space left creates something that it seems to tell the system there was a minor there, because even after 17, they wouldn't have received the stimulus anyway if they were dependents, but as I said, the blank space is creating something that is making PS calculate the stimulus as if they qualify. I realized this because I completed a completely new return with the same tax payer without the two dependent and the stiumulus was calculated right. I recommend that everybody be aware that when we erase a dependent whose information is transferred from last year, double check the calculation of the stimulus because  PS will give her/his the stimulus. Hope an employee will take note of this.