First and foremost let me address the sides of play-style that are in question.
Stealth haters that would complain/show great distaste for those utilizing such mechanics such as stealth.
What we know is that the patch @ https://en-forum.guildwars2.com/discussion/60248/game-update-notes-november-13-2018#latest has brought some styles of stealth play-styles to their knees while making some other forms of play easier and able to detect easier. However those that enjoy veiling / entering stealth to get behind enemy lines or even those that used to scout have either stopped playing wvwvw or moved on from the game altogether or even stopped the classes they have enjoyed playing.
What are some suggestions that would appease both sides of play that could bring those players, that stopped playing, back to the game and at the same time still make it easier for those players that are against such stealth play?** Please leave your suggestions while staying on topic and explaining your reasoning. Be open to criticism and do NOT post low effort replies** If you can not post here, just pm me in game and I will post your suggestions here as an edit.
1. OP suggestion is: Make the marked effect from sentries/towers an upgrade in specific tier that could effect players as it does currently...however, would still allow players utilizing stealth to enjoy their play-style.