If it was just on the outside I would have suggested it could have come into contact with some form of spray (polish / air freshener / insect killer …) which had reacted with the plastic.
The likes of padded car dashboards and flexible cable can exude plasticiser, but I've never seen it on a TV case and would wonder why they would be needed on something that should be rigid? Plasticisers work by preventing full bonding between molecules of the base plastic, and the un-anchored plasticiser molecules can migrate to the surface, especially under heat. Plasticisers contributed to the 'new car' smell in the 70s/80s; and can also the reason that flexible cables left undisturbed for years have a coating of grime – nothing to do with static but that the dust sticks to the film of exuded plasticiser.
If it was exuding like plasticiser, I think it would just be a surface film rather than the blisters you describe – that sounds more like a manufacturing defect – maybe the back was laid up from an impregnated mat but the materials weren't properly prepared or processed.
I would suggest it would still be worth contacting the vendors as there might be a latent defect which is emerging which they might already know about and/or might wish to investigate.
Regarding 'could it be dangerous or toxic' I would suggest treat it discretion until you know otherwise.