Cat panting when stressed

I noticed a few month back that when I decide play time is over my cat will start meaowing super loud (in protest) and a few times she also started to pant!

Few other occasions where other potentially stressful situations like when I had to restrain her or close her in a space. Like when she doesn't want to do something or doesn't want to be somewhere (eg: inside the carrier) she will start as a protest to meaow and then panting/hyperventilating.

But I noticed she does this also when she wants something/ wants to be somewhere but I will not let her. Then she is also loud and panting.

Of course this is not a regular thing and it doesn't happen on every X situation, but it happened definitely quite some times and I never really experienced it with other cats.

We did some lungs x-rays and also ECG a couple months ago before spaying and everything seemed normal.

I am just wondering if I should worry like - could this be bad? If she gets stressed during a trip for example and there's no way to intervene could she have a panic attack? Heart attack?

This was never the case but since she does do that I am wondering.