Thank you for the video. Again, it helped a lot. This time, as suggested in the video, I used surface blur with blend mask - chromaticity. However, in addition, I had to tune the r/g/b values in the module to very high values, around 0,3 and more.
There are some side effects, like a bit of blur for other parts of the photo and some color shift towards purple that you can see on the verge of the shirt. Can I somehow add a draw mask on top of this to limit the effect to the shirt only?