There are couple of things to be aware of; firstly, it could be related to the HRT (the brand, dose or method of delivery). However, it could just be a coincidence too.
Perhaps it’s worth just seeing if there’s anything that triggers it in particular. For example is it worse within a few hours of adding a new patch, if you’ve been doing exercise, after eating or drinking different things, potential allergies that could be exacerbated by HRT perhaps. The easiest way to do this is with a notebook or diary that you can use to record times/dates you get the breathlessness and also things like what you eat and drink, what you do during the day, when you add a new patch etc…
If it definitely feels like it’s HRT related then trying a different type might make all the difference. The reason is because not every type of HRT suits everyone and it can take some time to find one that’s right for you.
And of course, it goes without saying, that if you’re breathlessness gets worse or you are concerned about it, then a trip to the GP is a must.