This is not a bug nor glitch in their app according to the news below "The impact of enforcement action against Binance.US is affecting the prices of cryptocurrencies on its exchange" And according to the news, it's a crypto discount it is ranging from 2% to 5% discount.
That is why you see different prices on the BTC/Fiat compared to Binance.com and according to the news, not only BTC is affected by this also other Crypto/Fiat pairs like ETH.