Update 23rd June 2023, as of today I am seeing the volume of disapprovals for this specific issue drop, however no official news from Google that the issue was resolved.
Starting June 21, 2023, you may experience a substantial number of unavailability incidents for both desktop and mobile landing pages. The issues will primarily include Timout on DNS Lookup, Page not found (404), and robots.txt on the server is unreachable.
This is not an issue with your website but a bug from Google’s crawler (not confirmed, but most likely the reason).
I have sent @adsliason a message to look into this on twitter. You can check the tweet for updates or check this article as I will update it once its resolved.
@adsliaison Can you look into the massive crawl errors in Google Merchant Center, such as timeout dns lookup, robots.txt unreachable and 404 errors. These are not website issues as its happening to a lot of clients. Thank you.
— FeedArmy (@FeedArmy) June 22, 2023
This happen with me also