I made a transaction, sending bitcoin to a crypto wallet.
It took 3 days before the bitcoin was received in my cryptowallet. What could actually be the cause of this delay?
You need to share what is the crypto wallet you sent your bitcoin to. It is important information because there are two possible destinations for your bitcoin.
#1: The address belongs to your account on an centralized exchange or an online platform. That is custodial wallet, and you don't own private key. You must wait that platform to detect your deposit, its confirmations, and credit it to your account.
#2: The address belongs to your another non custodial wallet. With this, you have private key, and you control your coin. Sometimes, even your transaction is confirmed, but if you have issues with wallet connections to nodes, servers, you might not see the confirmation. But because you have full control, you can configure your wallet and fix connection issues.
With #1, if that exchange or online platform relies on, uses a Payment processor from another company like Bitpay, that has problems temporarily, you will not see your transaction, deposit credited to your account. Contact their support service to fix it.
The company can wait for BitPay for example to fix problems and broadcast transactions, credit deposits automatically or the company can broadcast, credit it manually for users in waiting time of problem resolve from BitPay.