There is very little of a problem currently. It's mainly that people don't know how to read and judge 0-conf double spends. Some of them should be expected and do not signal anything abnormal.
However there is a concern with potential sub 0 sat/byte transactions, which can be used to exploit a payment later sent to a merchant. It's not been used a lot or potentially even once as far as I know, but it could be and there have been some suggestions on how to fix it.
In either case I hope there can be a move to sub-blocks or similar to entirely remove almost any potential 0-conf concern.