I wonder what Hacktoberfest would look like now if they were still giving out t-shirts to everyone. Probably not enough cotton in the world.

It can't be on individual maintainers to stop this, imo its on Github (and Gitlab) to stop these sort of accounts from even getting to the point of submitting PRs. Its essentially spam.

Look at the user who created the first PR they reference https://github.com/Samuelsills. This is not an account that should be allowed to do anything close to opening a PR against a well known repo.