It's not that they don't like it but they usually aren't used to it. Especially going from a small space to a bigger space, if you don't provide enough hide outs or plants (real or fake doesn't matter) then the Betta can get stressed and you may see clamping of the fins, sometimes they surf their tank but that's debatable whether they are "stretching their fins" so to say or chasing their reflection or wanting out. Many different things to that one so I don't find that one to be a reliable way to tell. I think mostly just clamping, hiding, staying to one corner, being shy unless already shy then those would be things to be noted.
But they usually get used to the tank no problem by the end of the week. Something to help is when they go in, keep the light off for the rest of the day and all night, it helps keep them calm and they'll like their new surroundings much more. And then there are fish who don't care where you put them; they're just content to be with you