Why are there so many recipients when I send money from one exchange to another?
When you bought bitcoins on Bybit, Bybit added the corresponding Bitcoin balance to your account. Your request to withdraw your funds to your Coinbase wallet caused Bybit, in the role of the custodian of your funds, to issue a payment that sent the funds to your wallet (and reduce your balance with Bybit accordingly).
Bitcoin transactions may perform multiple payments at once by assigning funds to multiple recipients in separate transaction outputs.
Presumably, Bybit is a large enough service that many other users requested withdrawals around the same time, and this allowed Bybit to batch together all those payments in a single transaction. As every transaction needs at least one transaction input, a transaction header, and usually a change output to assign the remaining funds back to the sender, payment batching is more blockspace efficient and allows the service to reduce their cost per withdrawal.