Safe frame or not? Pin hole!

[Ming the Merciless]

Just from pictures I’ve seen online with the same paint design. It’s heavy only in those areas.

Never mind photos online. Take photos of other chain / seat stay junction from sane angles you have already shared here.

 

[Milzy]

I’ve tried to put a very fine sewing needle through but it just stops which is good news. Maybe a bonded tube inside.