Related product SEO

Hello community,

Using woocommerce and storefront (child) theme, I have automatic related products at the end of each product page.

At the bottom of the page, the title “Vous aimerez peut-être aussi…” (upsells product) and “Produits apparentés” (Related products) are in H2.
And the products are also in H2. Which make a lot of H2 in the page.

I am not SEO specialist but I would think it could be muche better to have the titles in H2 and the product in H3.

Is there a way to do it with simple code without slowing down the page by additionnal CSS ?

The page I need help with: [log in to see the link]