Bitcoin's block reward system cuts in half every four years, a process known as "halving," which decreases the rate of new Bitcoins being produced.
This system will continue until around 2140 when the limit of 21 million coins is reached, and miners will then receive fees for processing transactions.
As of April 2023, about 19.3 million Bitcoins were in circulation, leaving just around 1.68 million left to be released via mining rewards.
This rally is being attributed to the upcoming 'Bitcoin halving' event, which is set to occur around April 2024.