According to the classical Indian school of logic (Nyaya), which fallacy is committed in the statement 'All things are non-eternal because they are knowable'?

The statement commits the anupasamhari fallacy.

Its subject "all things" leaves nothing outside as an instance.

With everything included, no example lies beyond the subject.

The reason "knowable" then has no positive or negative case to confirm it.

A hetu with an all-embracing subject and no external example is anupasamhari.