It took more than an hour to mine a single bitcoin (BTC) block on Monday, leaving thousands of transactions stuck in an unconfirmed state.

According to several blockchain researchers, the interval between the last two blocks mined by Foundry USA and Luxor was 85 minutes.

According to Mempool, more than 13,000 transactions were on hold before the last block was mined.

Bitcoin underwent an adjustment in mining complexity last week to ensure that blocks are confirmed every 10 minutes. With mining complexity rising to 35.6 trillion, bitcoin mining is becoming more expensive, putting pressure on the mining industry, which is facing rising electricity prices and a bearish cryptocurrency market.

It is currently unclear why the confirmation of the latest block was delayed.