Many have opined that the proliferation of veils has had negative repercussions for balance. That's probably true, but I think, for the most part, individuals with veils are a minor problem.
The bigger problem seems, to me, to be that this proliferation has lead to a somewhat novel phenomenon of raiding parties that are entirely veiled. In the past, you'd have a few veiled people in a raiding party, but could follow the bulk of the party by tracking the ones without veils.
The only real solution we have right now is to rely on people on our side who have veils. It's already happened a few times since I came back from dormancy that we've had a fully-veiled enemy group raiding the city and no veiled citymates around, which leads to tremendously silly situations where half a dozen people are raiding our city and we can't do anything about it without combing every room of the city by hand (in which case they just pop over to a new location and try again). The alternative, when there are veils present, is usually for citymates to act as automatic radar stations, triggering to repeat locations to channels at regular intervals or, worse, offering automatic replies with locations to tells in certain forms (this latter one seems to be common among veil owners now). Worse yet, both of these can and are done while AFK, making the "radar station" metaphor even more unfortunately apt. I think there's general agreement that this is precisely the sort of automation that's sort of distasteful from an immersion perspective.
The suggestion then, is to make veils stop working when the veil owner is being followed. It makes a sort of sense, since their location is, in an abstract sense, being constantly "revealed" to someone. More importantly, it means we can't end up with entirely-invisible raiding groups nearly so easily. Better yet, it affords defenders an active defence against veils - the more sneaky defenders can try to follow veil users in order to negate their veil.