The investment giant BlackRock questioned the unchangeability of Bitcoin's issuance in its new video — Satoshi Nakamoto initially laid out a maximum supply of 21 million coins in the protocol, which is the most reliable protection against inflation.
Yes, issuance can be changed through a hard fork, but such a network will no longer be the real Bitcoin. That is, any attempts to change the figure of 21,000,000 will simply lead to the creation of new networks, rather than an update of the original BTC.