Not anymore in the coming bull runs, with the development of the Liquid side-chain in my opinion. I believe the Tether.to CTO also said that they will use the Lightning Network as a platform for USDT issuance.
Lightning Network and Liquid are two very different networks though. while i have not seen any traces of centralization in LN so far i have seen some red flags indicating centralization in Liquid.
as for Tether, i believe they will start an LN network eventually like some other altcoins but it still has to be settled on bitcoin blockchain since unlike those coins USDT doesn't have its own separate blockchain or network.
I wouldn't call them "red flags" in Liquid, they are trade-offs. Plus token issuance is always centralized, which USDT issuance is something like, in ANY network its developers are choosing. You trust that the issuer will not scam you.