Quick PSA: If you share me a tumblr link that looks like username.tumblr.com, I can read it! however if instead its formatted tumblr.com/username then instead of actually being able to read your post, I get this highly annoying screen and can't actually read the post you actually sent

If you were just passing along a silly meme or something, maybe it's not worth the effort of double checking that everyone can actually see the post and that's fine whatever. But if you're sending it because you think that the contents are important enough that people off tumblr should be reading them? Maybe double check

btw if you're going "wait that other URL doesn't seem to be available for my blog????" go to settings/blog/yourblogname and turn the "use custom theme" toggle to ON. No I don't know why subdomains are only available with a custom theme, sorry tumblr's just Like That these days