Mobile Usability

The Google Search Console also shows you which lines the errors refer to, for example. Especially with the font size, this would be a clue to enlarge the text in question.

I tested 2 things:
Once there is actually content that is too wide, even if only a few pixels.
And I suspect the small font size is the price.

Hence my suggestion for a solution:

@media screen and (max-width: 959px) {
	body.page.content-max-width .entry .alignfull {
		margin-left: 0;
		padding: 0 5%;
	}
	.wc-block-grid__product .wc-block-grid__product-add-to-cart, .wc-block-grid__product .wc-block-grid__product-onsale, .wc-block-grid__product .wc-block-grid__product-price, .wc-block-grid__product .wc-block-grid__product-rating {
		font-size: 1.1em;
	}
}