I use Joy Non-Ultra, but i've tried JnJ and a few others, they all follow the same 1oz per gallon rule, which comes out to 8 mls per liter (or quart, or basically a typical commercial spray bottle). I mostly use 10-12mls per liter. Back glass add 2mls extra for a little extra slip. I'm not a fan of JnJ, i know a lot of other people are big fans of it, but i think it has weak adhesion, just my opinion.
JnJ or Joy or Dawn all have the same exact mildly caustic acid sodium hydroxide, they all require an acidic component to be a soap and JnJ has it as well, only difference with JnJ and dish liquid are what they add to JnJ to keep skin soft, otherwise why would they create JnJ if it didn't clean your kid? If you use any dish liquid make sure it is NOT Ultra or Concentrated. If you use Joy Non-Ultra or Dawn Simple Clean for slip it is very mild but not what you want to clean with, you would use Dawn 4X or any concentrated/ultra dish liquid to clean but not for slip. Joy Non Ultra and Dawn Simple Clean are not going to eat your adhesive, they both have the same mild acid like all soaps do (including JnJ). JnJ and Joy Non-Ultra would both be eating the adhesive (i've never seen "eaten" adhesive). JnJ is probably more likely to soften your adhesive more than Joy would "eat" it. In the end use either JnJ or Dawn Simple Clean or Joy Non Ultra because apparently they all work well for whoever uses them. Just don't use anything Ultra or Concentrated. Look on Facebook, they have a guy Mike doing multiple videos pull testing dried film and showing that Joy beats JnJ every time, in fact JnJ came off the easiest and Joy is the hardest to remove with Tint Slime being a close second. If you saw that video you'd rethink JnJ, if you like JnJ then you should use Tint Slime because it's similar without the stuff that is not good about JnJ. Most important about all slips, squeegee it all out. In the end use whatever works for you, just find me a written test that says states clearly that dish liquid is bad before saying what you heard.
With dish liquid for slip, it all boils down to NOT using Ultra or Concentrated. That's also where the confusion lies when it comes to dish liquid as a slip. My 2 cents on it.
