My drain bolt has done the same thing. I figured it was a design failsafe too. Finally stripped either the bolt or pan. Can't tell because when I look at the end of the bolt there are 2 layers so either it is made that way which would explain the weird tightening or when I stripped the pan the threads came off with the bolt. If I can get the Toyota replacement, maybe I will be able to tell.

1997 T-100 4X4 Xcab,Warn Hubs
02 Camry LE
2008 Yaris