I had a loose toliet, I thought the bolts were bad....

I have a PVC type closet flange that was simply nailed to the
subfloor.
The nails rusted and there is nothing holding the flange to the floor.

So I poped the flange up, and the flange was never really installed to
the drain pipe.

The flange has a rubber ring which looked like it would engage the
plumbing.

The brand of this system is Canplas Industries.
I am trying to find a photo online...

But maybe this is a standard type system?