Simple and yet very convenient solution from the exchange's end is to no longer allow people to deposit funds while they aren't verified yet. There are already exchanges with this policy, and I think it should be operated on a much larger scale. It makes no sense to allow people to deposit funds while they have no opportunity to ever withdraw anything without walking themselves through whatever form of verification.

It saves exchanges plenty of time time as well, because all these people with stuck funds are constantly spamming support with tickets and whatnot while it could have easily been prevented. Imagine how many people ran into these problems just because they were too hasty to realize that centralized exchanges can seize their funds at any time of the day.