https://sprydigital.com/blog/wordpress/popular-content-management-systems-wordpress-drupal/
Its the same source, just different breakdown. Of all the websites they found using a CMS, 18% use wordpress. While 27% uses wordpress, which accounts 1/4 of websites in top 100k category uses wordpress.
In top 10k websites, 25% of the websites use wordpress, which is 1 of every 4th website is wordpress.
If someone thinks you can prioritize as a search engine some type of CMS rather than the quality of the content surprises me. Like, i dont have so much trust at Google - but why would they try to prioritize something like CMS? We all know core web vitals is a mere tie-breaker, so it cant be that.
A ranking factor could be longevity, that you have paid your domain the next 5 years or so - but that will only get a initiate ranking boost not longterm. Google sandbox doesnt exist, thin, poorly executed sites with the thought of (i will optimize as I go) are the reason for sandbox.
Also, headless CMS, like sanity - is actually worse for SEO.
https://www.onely.com/blog/google-needs-9x-more-time-to-crawl-js-than-html/ here is just one blog of rendering time and indexing time by using Javascript. So if you are running a blog on a javascript site, headless cms, "clean" cms - you are at a disadvantage when updating your content, or producing content.