While PCI DSS 4.0 says nothing specific about TOTP, it on page 171 also has this phrase about certificates:
"A digital certificate is a valid option for “something you have” if it is unique for a particular user".
So it is not an unreasonable analogy to claim that the TOTP seed stored in a desktop application is also "something that you have", as not having it prevents you e.g. from logging in from your friend's laptop.
While PCI DSS 4.0 says nothing specific about TOTP, it on page 171 also has this phrase about certificates:
"A digital certificate is a valid option for “something you have” if it is unique for a particular user".
So it is not an unreasonable analogy to claim that the TOTP seed stored in a desktop application is also "something that you have", as not having it prevents you e.g. from logging in from your friend's laptop.