Andrea, maybe a comment should be added instead to prores_ks.pro? Because when I tested 2 different rendered files although playing them looked the same, I used "vfy" to compare the output from existing prores_ks versus with the "vemdor=ap10" and internally something is different. And when I do a "mediainfo" on existing, I get "Writing library lavc" (which I believe means libavcodec and is open source) and on the changed one, I get "Writing library Apple".

Sounds like a really good idea to put it in the preset so users are aware of its existence as a comment but not sure if that would be controversial to Apple.

What do you think?

PS: I propose a very small change to the "prores_ks.pro" preset. The
addition of the "vendor=apl0" option is to make the various programs
believe that it was rendered with the official Adobe engine. I don't
see any difference, however I propose to leave it in this preset
anyway in case some people might find it useful and solve some
compatibility issues. I attach the preset.