You should be more specific in your posts.

I'm gonna assume you are talking about 1% or greater discrepancies, which means you might not be using an actual exchange. Read this: https://bitcoinmagazine.com/markets/ftx-collapse-cause-huge-bitcoin-price-spike

And then read this: https://nakamotoinstitute.org/mempool/everyones-a-scammer/

They don't. What you're seeing is a $50 difference on a $26,000 asset.

($50 / $26,000) x 100 = 0.19%

Bots will always arbitrage any relevant price difference, and the difference in price per platform is mostly related to transaction costs.

Significant price differences are something you see on low volume p2p DEXs, where a $2500 BTC buy is considered large.

Exchanges are made up of order books, filled with orders to buy and sell certain quantities at certain prices. These orders can only be filled on the exchange with which it is placed. So each exchange has a different set of open orders. The state of the order book determines the price on each exchange, somewhere between the current ask and bid prices

They actually dont (in any meaningful way) because they get arbitraged. If the price is significantly different on some exchange it typically means there is an issue with that exchange. They either restrict withdrawals, use stable coin in a btc pair that depegged, …

they are centralized exchanges