Blocked due to other 4xx issue
These pages aren’t indexed or served on Google
I can’t see any links to that URL, it’s only appearing in the recommendation block as the data-url that I believe is used to call the API? Couple of questions.
How is google seeing this URL?
Is adding it to robots.txt as blocked the best way to handle it?
You should first figure out on what pages google is finding that path and figure out what is the source.
Check any sitemaps as well not unlikely someone may have added it to a sitemap if you’ve had any custom SEO done.
Generally that url being crawled should not be happening as the route in most themes is only present javascript and /recommendations/products shouldn’t ever be a direct link to that endpoint it would be like cart/clear showing up in results.
Unless now goggle bot et al. are checking html tag data attributes for a “url” keyword to infer link, or crawling ajax request endpoints which would be wild but not surprising.