What's with the debug error messages, like VMDPE_1|1_VMDPE?
Your incoming buffer is not big enough to handle the data that you're giving it. Cutting away the comments from your code:

char incoming[3];


This declares a buffer for two characters, allowing for the (required) 0 on the end. println() needs to know when to stop printing characters: it does this when it sees a NUL (0) character.

Serial.readBytesUntil(',', incoming, 3 ) ;


You're passing in that you want to read 3 characters - but that completely fills incoming, leaving no room for the trailing NUL (0).

Serial.println(incoming);


This then prints the first character, the second character, the third character... then the 4th, 5th, 6th, 7th etc. in memory until it finally reaches a NUL and then quits.

What you call "debug messages" are actually printed gibberish in memory... To fix it, you need to make incoming larger.

Also, it's a good idea when using buffers like this to use the sizeof() function, as follows:

Serial.readBytesUntil(',', incoming, sizeof(incoming)-1 ) ; // Note the -1!