SEO problems with blog posts layout

Olesia Member Posts: 1

Why is the first heading in blog post h3 by default? It's not a good practice and how do I change it to H1?

Open Graph meta doesn't validate and the URL is obviously wrong in OG.

How do I add TOC and reading time?

The featured image is loaded in background and in order for it to get indexed, I have to duplicate it in text.