Mini fridge putty tape function

I have a mini fridge, and I noticed that it had two pieces of black putty tape on the refrigerant lines. What is the purpose of these?

They’re much thicker than standard tape and the best way to describe them is as a putty with a strip of cellophane backing.

My best guess is that they’re intended to seal some hole in the line or reinforce a weak weld or something, but that doesn’t sound very safe since R600a is the flammable compound isobutane.