Assuming you're working in a team, stale PRs aren't uncommon, they're just more indicative of a prioritisation problem in the team. A bot cannot help except to serve reminders that it is still open.
Whats your use case here? Do you need a reminder or something that can assign reviews? Or something that can automatically review code? There are few different ways to skin a cat
Most comments in the PRs are: “I think you should write this like...”. Just another person (AI in this case) doing a review.