It's mainly a texture/concept thing, my food needs to be safe from disembodied muscle, fat, skin, cartilage, bone, minced meat containing the combined flesh of thousands of raped and tortured carcasses, the faecal matter and bacterial colonies all meat is covered with, and the horrifying possibility of meat containing hidden cysts full of pus, bits of hair, teeth, genitals, eyeballs, parasites, tumours, zoonotic diseases, prions, etc.
Lab grown flesh would hopefully be exponentially cleaner, and far less problematic than the current rape torture factories and abattoir system, but I will never be able to thematically seperate labgrown meat from what meat currently is, not enough to be able to put it in my mouth and chew it anyway.
Also, all sentient life (as we know it) is made of flesh. Lab growing billions of disembodied chunks from a handful of sentient animals? There is still deep horror to this. Granted it's on a completely different scale to the current system of livestock atrocities, but it's still horrifying none the less.