How does Binance calculate the open and close values in the candle plot for Spot Trading?

Hello. I've heard that the open and close values are related to the primary and final transaction of the time vary (day, week...). Nevertheless, I observed the open value is identical as the close value of the previous bin, which sounds weird to me. As cryptos are decentralized, shouldn't we've got totally different values for that? Couldn't we've an outlier transaction within the first transaction of the day that's totally different from the final transaction of the day before today?

Also, prices within the dashboard (Spot buying and selling) are calculated based mostly on only Binance transactions or other external sources (like other platforms)?