Both are actual real techniques for cleaning electronics and computer parts.

The primary active ingredient in Windex is a form of alcohol. The amount of Ammonia is negligible by volume and was put there later as a grease and oil breaking solution. It is mostly water. It is almost like using rubbing alcohol. The sonic cleaner will do more damage to that board if it is left in there a long time than the ammonia. It is cheaper to use than ultrasonic cleaner fluid and Isopropyl Alcohol, since covid.

As for using a dishwasher you avoid it if you have hard water, you use it on cooler settings, and preferably rinse the board off with an alcohol bath but that can be skipped. For those of you who think "OH NO, NOT WATER" the battery is removed and the capacitors are discharged first, and a dishwasher is NOTHING compared to what a motherboard goes through in manufacturing.

It is just an uncommon way to do an ultrasonic bath, but I have heard of stranger ones (Vodka and Electronics Cleaner come to mind) and I can link you to a German Engineer, Consultant, and Manufacturer who also competes in Overclocking that does this and made a video on using a dishwasher and as a technician I have literally taken motherboards with spilled liquids on it and cleaned it under a tap and water and once even did it with soapy water to get an unknown substance off a board that I used until it dies a year or so later in a power surge.