my refrigerators compresser is making a loud thump when the cooling cycle stops, its geting worse and worse. whats up?

Re-design7 years ago
What it sounds like to me.

When the compressor stops there is a lot of torque on the housing.  There are 3-4 rubber bushings that absorb the vibration of the motor running.  One or more of these are wearing and need replacing.

Or it might be something else, but I don't think so.
if it's not the mount, its the compressor itself.  With seals the motor itself, and seals wearing out - the system starts to finish its cycle with a bad amount of pressure in the wrong place, then when the power cuts, thunk - the pressure forces the motor to do something it doesnt like.
I'd go with redesign's idea - anything else, and you'll be in new compressor land.