I noticed quite some time back that chicken bought from M&S and a few other places - the texture was not meaty / strand-like and low on flavour - almost rubberlike - then spotted a TV programme on processing of chicken in Holland I think for supply to major supermarkets where the chicken was injected in multiple points and tumbled in water to increase the weight. Thereafter, we stucl to buying fresh chicken from local butchers only - far superior in flavour and texture back to how you would expect it to be.
https://www.theguardian.com/environment/2013/dec/06/chicken-tumbling-water-industrial-practice-additives
https://www.theguardian.com/environment/2013/dec/06/chicken-tumbling-water-industrial-practice-additives