Testing robots.txt files made easier | Google Search Central Blog | Google for Developers
Glenn Gabe on Twitter: "@AlexisKSanders BTW, the robots.txt Tester in GSC also ignores a /robots.txt directive. So they baked in that functionality to show it won't do anything. :) You can test
Robots Exclusion Checker
Google's Robots.txt Tester | Google Search Console - YouTube
Bing's new robots.txt tester can help SEOs identify crawling issues