Propane fridge goes out.

Tiny mud (dirt) daubers are notorious for building nests in burner tubes. I'nve had it happen.

If you can hear the flame, and its nice and bluish, doubtful that cleaning is the problem.
I would consider it normal to blow out once in a while, especially on 2 lane roads, and in a cross wind. And in reality, it doesn't hurt anything, as long as you remember to check and relite it.

Usually RV fridges respond amazing well with a very simple ten seconds of blowing out with a compressed air blow gun. Remove whatever little covers are over the burner and gas tube, and blast it all out. Most of the time that’s all it takes and the thing works like new.

How do I clean the burner?

check the baffle and burner. that burner is VERY small, very low BTU, doesn't take much to cause it to not burn properly. take out the orfice, blow it out, blow out the line to the burner clean out the burner area. and blow out the crud around the baffle and any rust etc. from the exhaust.

clean the burner.

x2 good advice, they do need to be cleaned, if you can,t do it? hire a local rv tech .

Sounds like an air flow issue. May have to install a baffle at the outside door and/or a diverter in front of the roof vent.

Would also do a "burner area tune-up", as debris in the burner tube make them more prone to being blown out.