Are swappers considered Centralized even though they dont ask for KYC?
I'm assuming yes, because they have the ability to hold your funds, if it is flagged as suspicious.
Most DEXes are technically not centralized in the way that they don't hold your funds centrally - but rather making you deal directly with the other trader - but DEXes need software to run, and most of that is hosted on someone's servers which are centralized. Although there are a small number like Bisq and Uniswap are completely decentralized and run from some blockchain.