China being incentivized to find evidence supporting the CCP's desired image absolutely does affect how likely it would be for such evidence to surface if it exists.
We see virtually no such evidence; we can assume that's not because China's lack of trying to find it; which should adjust our prior against such evidence existing at all. Yes?
Reasonably convincing evidence, to me, would be:
- genetic precursor virus particles which have died and no longer exist - they are extinct, or,
- dated blood samples with immunological evidence of infection, sufficient that it isn’t just tampered/false positives. There’s no reason to expect this would have been collected.
i.e. if you haven’t collected it by 2019, there is never going to be any evidence.
This also answers your sibling commenter: it’s not in China’s interest to publicise any such search, when the odds of discovering anything (even if there were earlier infections) are vanishingly low.