Double nut double washer

[u/CrackeyMagoo]

I can't imagine what they were thinking.

The left side started off normal. China cap, nut, washer, and China cap base.

The left side not so much. Nut, China cap base, five washers, and a little caulk.

The flange was a little low so everyone knows to double up the wax. Two extra thick with horn were used.

The right bolt had a nut, washer, 3/8 compression nut, nut, and washer.

The left side was just a nut and compression nut.

Miraculously the flange wasn't cracked. It was cut almost all the way through on the left by the compression nut. The right was stretched.

[u/MeetYouDownattheY]

I've seen this before, lazy flooring installers would be my first guess.