Creality CR-10 v3 under extrusion issue

The issue is difficult to explain in words, so I have attached some video documentation. As you probably will read out of the explanation, I am quite a novice in this game. So I sincerely hope that there is someone out there who would like to provide some advice.As the video shows, the extrusion is very thin and not consistent. The printed subject is becomes very “loose” and of course not stable.The issue started after installing a BLTouch and at the same time migrating to Marlin’s latest version firmware.The software seems to work, although I had a little bit of difficulties adjusting the Z-offset. In fact I managed during the process to run the print head against the bed :-(What did I try to solve the problem: - I tried opening a brand new filament package to ensure that I did not have a humidity problem - I tried slowing down the print speed - I tried increasing the nozzle temperature - I changed the nozzle and the tube - I checked that the filament moves consistently - it seems like it - I adjusted the Z-offset several times and after adjusting the Z-offset, when I move the print head to zero Z, I can exactly feel some resistance when moving a paper under the print head. So I assume the calibration is OK.After the above exercises I am about to give up and stopped for a while reading further forums. Instead, I am hoping that someone out there can provide some advice.Please find a couple of videos here: https://1drv.ms/u/s!AtGt1Q5H3XsPit8P...h-ieQ?e=TGR3Vd Thanks guys…