Looking at your two pictures regarding the paint not the picture of the whole rear. The first one looks fine, its the second one I think has been repainted. There should be a mild orange peel texture which is shown on the first picture and looks like the factory paint but the second picture its very unclear looking which is the sign of a respray. It should shine rather than glare. Touch that particular area, if its not smooth then yeah its not done well.
If that's the only area that looks this way then it looks to be minor accident with mere cosmetic damage and nothing to be paranoid about regarding the accident history.
Inspecting rental cars and the quality of body shop work done was something I did not too long ago. If I caught this, I would've requested research and if it was one of our vendor shops to re-do it.
These pics are more extreme cases of what appears to be your issue with this paint.
From your pics the area is very small, if everything else checks out then you could live with this minor cosmetic defect as its on the plastic bumper cover rather than the metal where perhaps there's more of a concern for the long term.