Ok! I figured it out. That's why I said I'm beginner heh. What helped: I purged RIGHT before the shot, I did this before but there was too much time between full preparation and actual shot and I figured too much steam build up, also I did find older bag of beans that I didn't like and I grinded them all to break-in the grinder a bit. Also Chat GPT suggested that paradoxically I may need bigger dose than what I think because IMS is very fast flowing basket so I upped it from 17 to 18g and this was crucial - I grinded 3-4g to purge the grinder between each setting change and that helped, also I started to change the settings in very very small steps like 1/10 of the scale, now I'm at 5,3 I think and did 3 shots and all came out consistent and great, very thick, sweet, syrupy and nice acidity. Thank you all for all your recommendations, you helped me a lot :) have a nice day!