There is no cryptocurrency in my view that is a safe haven. The only purpose of fiat pegged crypto currencies aka stablecoins is to hedge against a drop in price of other non-stablecoins cryptocurrencies. Different stablecoins have different risks and the safest would be an actual fiat deposit 1:1 to the stablecoin and that fund must be safely stored somewhere in some account. This process should be audited regularly by reputable auditors and the reports made public. The rules of the fund should be that at any time when a stablecoin holder holds one unit of stable coin it should be possible to convert that to one fiat unit. Of course there will be logistical limitations to this but this should be the rule. Then that stablecoin will have less risk. It is also possible for stablecoins to have other types of reserves  and assets to serve as collateral for those stablecoins but those projects' risks are higher. There are clouds and uncertainty hanging over USDT so it is uncertain how "safe" USDT is.