PullRequestPrunerBot is responsible for closing PRs that have not been active for a certain time. However, it currently doesn't ignore comments from bot users when determining the latest action time of a PR.

https://github.com/openjdk/jdk/pull/17401
For example, in this PR, the bot did not close the PR because the bot user updated the "ready for integration" comment, despite no real user activity for a long time.