The story of copyright in the twenty-first century tends to be one of corporate overreach, though you perhaps can't blame big business for trying; after all, it falls to regulatory and oversight bodies to rein in the worst actions and instances of IP abuse, and those institutions don't always appear to be up to the challenge. That's not to say the overstepping companies bear no culpability, just that you can't expect those corporations to act in anything other than naked self-interest, and in the absence of someone telling them "no" they might assert rights they have no basis to claim.
As explored on The Verge, the approach of Disney+ to essentially claiming rights over an entire hashtag caused concern and confusion. Setting aside questions of whether anyone can just stake such a claim over thousnnds upon thousands of tweets, it's dubious that the legal disclaimer offered in Disney+ tweet would hold up, given that #MayThe4th tweets would be coming from countless individuals who don't follow Disney+ on Twitter and thus never saw the terms and disclaimers. That tweet was confounding enough to prompt a second tweet clarifying that the terms only applied to those using #MayThe4th and mentioning @DisneyPlus in their tweet, which may or may not be a more defensible position; it's a question as to whether someone actually follows Disney+ or read the specific tweet to necessarily tweet at the account with the hashtag.
But the benefit of being Disney is that legal ramifications only exist insofar as people are willing to pursue them, and in the case of the average Twitter user, the option to go after one of the largest entertainment conglomerates on the planet for a tweet isn't a real possibility. Disney may not be legally in the wrong in this instance, but it's not unfamiliar with an aggressive approach to copyright that could often be called overreach. We should be thankful it's only tweets they're seeking to lay claim to in this case.