Blooming can not be recorded with a screen capture, as this would only show the content of the video buffer. It is solely visible via in person or an external device like a still or video camera. You have to adjust for local lightning conditions, of course.
Blooming is caused by the mini led arrays in the backlight matrix and is part of this technology. The less led arrays are used the more blooming appears, as the bright led light source covers more surface area with its light compared to the pixels shown.
One can see it here, but it is to be expected. There is nothing you can do but wait for more high resolution mini led screens.