Fivestar has support for the Microdata module in the 7.x-1.x branch for Drupal 7.
But the Microdata module has never been ported to D8+, and has not had a single commit since 2017, more than 7 years ago.
Integration with the module still exists in the Fivestar code base, but has never worked at all in Drupal 8, Drupal 9, Drupal 10, and now Drupal 11.
While I do not object to having support for microdata in Fivestar, right now we have a bunch of dead code and absolutely no support from the community for fixing it or adopting the Microdata module, or answering microdata questions in the Fivestar issue queue, etc.
As a result, after 7 years, I think it's time to remove all traces microdata support from the 3.0.x branch going forward. The only thing that would change my mind on this is if someone would step up and write test cases to define the expected microdata output, along with a patch to fix and/or add microdata to Fivestar. If that is done I will be happy to maintain it in working order going forward, but I'm not going to do the research or the work myself to make that happen.
If microdata is important to you, please comment here and take steps to get this running again.
Needs review
3.0
Code
Automatically closed - issue fixed for 2 weeks with no activity.