If it had been used to fix the tiles it is a complete disaster. However it looks from the photos like your tiler has used the ready mixed adhesive bucket to mix up the grout (alot of us do similar). If it has been used to fix the tiles it will result in a failed floor sooner or later and yes, could well have helped cause your issues.
Thanks for that, there's 2 empty tubs, of the same stuff (One as you say appears to have been used to mix the grout in, but not the other, which only confirms my suspicions, that's what he's used, given it was only a floor that was being tiled (no walls)