capture the generated codes and time of input in some way, then brute force hashes until they generate one that produces the correct codes at x time
Given a TOTP key is usually at least 18 characters for a 6-digit code, having only one data point sticks you with something on the order of 10^28 possible keys for a given singular code (way more if case sensitive). You’d need to be regularly intercepting TOTP codes to brute force your way to the right key, and even then it’d only be valid for a single site. At that point it probably means you’ve fully compromised the connecting device or server, at which point, why do you even need the TOTP again?