Why does this sign appear?

Question

Magento

the question is, I add a widget of the last viewed goods, recently viewed, to the page,
everything is fine if it is a regular static page, block, etc.
But I wanted to add this widget to the content of amasty promo banners - there is an opportunity in different places of the page - product, category, search, basket - to add banners as images, cms blocks or just as html. In any case, either directly in the banner, or in the cms block after adding the widget, such a shortcode appears.

{{widget type="Magento\Catalog\Block\Widget\RecentlyViewed" uiComponent="widget_recently_viewed" page_size="4" show_attributes="name,image,price" show_buttons="add_to_cart" template="product/widget/viewed/grid.phtml"}}

So, if you add it in such a way, as a block or as html, then no previously viewed products are displayed, but instead of them I see this text.

{"store":"1","currency":"EUR","displayTaxes":"1","displayWeee":"1","allowWishlist":true}

Moreover, it is completely incomprehensible what this has to do with the widget, if it were not processed at all, and would be displayed simply as text, this is one thing, but I don’t understand why at all.
Interestingly, I could not find a simple discussion of such an error anywhere, this text is easily googled and it is even clear that people have sites with this error.