“TPM is a backdoor” was something that got bandied around during the Vista era psrtially by people not understanding and partially (imo) to muddy the waters.

Secure Boot was maligned as at the time only MS were allowed to sign for it, so it was just an anti-linux locker. Later, after much haranguing, they backpedaled and allowed Canonical and Redhat to sign things, much much later, we could self sign.

TPM was also maligned around the same since MS (allegedly) had aspersions to only allow signed software which would be encrypted so that ‘bad actors’ (the users themselves) couldn’t change ‘protected’ (any) executables. I think the closest we’ve ever seen of that is Windows S.