Someone mentioned that the pavers are made from plastic bottles that already deteriorate and shed microplastics into the environment. At least in dense brick form the surface area is dramatically reduced and the deterioration rate slowed.

Yes, the plastic in this case acts as a binder, in fact it would potentially be worse since the heating likely evaporated or decomposed most of the plasticizer which would make the plastic more brittle and more likely to wear off into micro plastics.