BTC deposits are made available for trading after 6 confirmations on the bitcoin network. Your deposit will remain pending until the deposit hits 6 confirmation (approximately 1 hour).
What are Blockchain confirmations?
Bitcoin deposit speed depends on the Bitcoin’s network traffic (i.e. number of transactions across all exchanges and wallets). During periods of high volatility, bitcoin network traffic is usually busier due to the increased demand for transactions.
Transactions are being added to the Bitcoin mempool's queue continuously. Some may have been sent with higher miner fees than the one sent with your payment. This means that when network traffic is high, miners may prioritize transactions with higher fees first and move to transactions with lower fees a little later.