It isn't because he got vaxxed they feel betrayed; it's because after months of downplaying Covid, making a mockery of masking wearing and suggesting multiple dubious alternative therapies for it, he had the audicity to finally tell the truth about the vaccines being perfectly safe because he wants to receive (undeserved) full credit and praise for their developments.
MAGA world is having none of it and turning on him. Even Alex Jones has gone on the attack declaring Trump him "ignorant" or "one of the most evil people that ever lived". Hilarious! Just wait till they finally realize he lied about winning the election too.