Somebody spun a good yarn! Apple does not have any “disintegrating substance” within or on the screws. They do use thread lock on some screws but thats not how they know you’ve opened the system. Visual damage is the biggest clue (scratches) as well as when the wrong screw was placed in the wrong location.
Legally any sticker that states is voids your warranty if removed has been argued in court and was over turned! Warranty Stickers are Illegal!
Now lets get to the brass tacks here! You want to open the system to check for water damage. Did you have a drink spill or drop your system into a puddle?
Sadly, these newer MacBook Pro’s are less repairable than the older models. The keyboard is not replaceable the complete uppercase needs to be swapped out MacBook Pro 13" Touch Bar 2018 Keyboard Teardown