This is the most uncharitable outlook on the increase of PRs. It may be true for some contributors, but any company reviewing their GitHub will see that the code is largely spam.
I think most AI generated code is people that want to help the project, but maybe aren’t familiar with the standards and norms.
If their AI model is good enough to make PRs, it's good enough for them to ask it about standards and norms. They can't be both massively enabled and helplessly unaware.
I don't have much charity in my heart for people using AI to spam every corner of the public internet with slop