What is this tumblr.com sub-domain?

So today I was casually browsing tumblr but when I checked Noscript it showed one sumbdomain I don’t remember seeing (or paying attension to) called -txmblr.com and -https://safe.txmblr.com which seemed little weird to me and I was not sure what they’re about. I cannot find anything really informative about them via google or some 3rd party scannes that show subdomain information (like Sucuri and/or Quttera). Quttera however shows one suspicious file , but I’m not sure if it’s one of those false alarms Quttera makes with some websites (like here: https://forum.avast.com/index.php?topic=179265.msg1268870#msg1268870)

http://quttera.com/detailed_report/www.tumblr.com