Of course not ! I would not have returned a cent, unless, of course, I had not been specifically asked about it. This is bug of the exchange owners and, accordingly, this is their personal problem.
I am sure that any major exchange will also receive substantial insurance payments if this happens, so you should not return anything to anyone.
And just like I've said here before, I personally would not have returned a dime from that 24 eth if it was me this thing happened to, trust me, except they contact me, then we will negotiate how many eth I Will return back to them, this exchanges don't send anyone of their users, they probably have stolen from their users much more than we all can ever imagine and maybe this is God's way of taking from them and giving back to the poor lucky guy😂😂,
And as an update, the exchange didn't contact the lucky guy up till now and the guy in return have not returned the eth, Infact, he spent some already.