I think the only way we'll know the answer to this is if Ring provides it, While I've had the cover off on LM-2S's and LM-3S's (the label adhesive did hold up against the weather here once!) I doubt I could identify a TVS diode just by looking at it. It would be a good answer to know though, RP modules are expensive and anything that one can do to protect them is a good idea.
- Tim