‘73 Charger – question on bodywork for potential purchase (see additional photos)

I’m looking at buying my first classic car (ditching my trash-quality Tesla for something old and cool that will be my daily driver around town, but also something to keep in excellent condition). Leaning towards a Dodge Charger or Challenger, and this Charger has caught my eye.

The seller posted these pics of rust/bubbling paint near the two lower corners of the rear window. I know nothing about spotting underlying problems in the bodywork, or checking to see how serious of an issue this could be.

To the knowledgeable people out there, do you think this is a sign that there’s serious rust under the paint? What would you do/look for if you were thinking about buying this car?

Thanks in advance!