I would expect both big and small companies to make incorrect bug claims.

I'm not even convinced that big companies will have a lower percentage. They have lots of managers that wants to know the progress. And that prefers to start alternative tracks as soon as a snag is found. So they may report a potential bug as a side track, while one ormore skilled developers spends more time with the datasheets, the software and the hardware and tries to figure out exactly what is happening.

Next thing is that a big company thinks it likely that the chip manufacturer will listen. So they believe there is a chance to get help even if reporting the issue quite early. A smaller developer (at least the skilled ones) knows that being small is problematic. So they will often try to set together a good test case to be able to prove the existence of the issue. All to balance their tiny weight.

It's just that it is far more important to keep a big customer happy. So there is a stronger incentive to have an application engineer try to try to quickly reproduce the problem.

Next thing is that there are few large companies but a huge number of tiny companies. So all the small companies can together create a "majority vote" about the potential for a bug - they are likely to try every single bit there is in the chip because of the large number of projects they represent.