There are a few ways of securing a shower pan drain.
My favorite way is using a caulked joint (lead and oakum) some of the Mustee brand type use a PUSH rubber gasket that can be driven in with a hammer and screwdriver when the jackleg tech doesn’t have the proper setting irons
Then there is the screwed type drain using a galvanized nipple, and of course the No Hub connection below and the Glue type for REAL butchers in this field.
If your pretty handy you can try to force it up and hopefully you wont do to much damage to the piping below. have fun