PancakeSwap is centralized because it lives on a centralized blockchain controlled by Binance itself. The Binance Smart Chain is nothing more than a "glorified payment processor" subject to the risks of a single point of failure. Things would've been different if Binance wouldn't controlled most of the network's nodes. The company decided to sacrifice decentralization, security, and reliability in exchange for scalability (low fees, and blazing-fast transactions).
Ultimately, Uniswap will win as it's the most decentralized AMM in the industry. It's suffering from high fees and slow performance because the ETH blockchain is extremely clogged. Things could change with Uniswap V3, as most operations will be performed in an off-chain manner. After that, Uniswap will be able to provide low fees and high performance to its users. PancakeSwap's rise may not last for long, once people experience the negative effects of centralization. Who knows what the future of these platforms will be as mainstream adoption for crypto/Blockchain tech grows towards new heights? Just my thoughts