Can you tell me please why there are no headings (h2-h5) in portfolio categories? Here is the example: https://artlevin.com/original-paintings-contemporary-colors-of-judaism/
Welcome to our forum.
as far i understand SEO, its not required to have "h2-h5" tags in the gird, i just checked your page, i can see there is already h2 tag in your page content. which seems to enough to maintain SEO,
we didn't keep h1-h6 tags because of style conflict, most of the theme uses different style for these tags and we found lots of hassle for this and repetitive elements(h2-h6) may cause SEO issue.
if you are concerned SEO issue please write a little bit in your content area(outside of post grid) and keep these tags, I hope this will be more helpful for SEO.
Hope you understand