The Shapella hard fork has officially been executed on the Ethereum Mainnet— meaning that Ethereum validators can finally withdraw their staked Ether (ETH) from the Beacon Chain.
The long-awaited upgrade took effect at 10:27 PM UTC on April 12.
Through Ethereum Investment Proposal EIP-4895, staked ETH was pushed from the Beacon Chain to the Ethereum Virtual Machine (EVM) otherwise known as the execution layer, making withdrawals possible.
It is the most significant upgrade since The Merge on Sept. 15 and it moves Ethereum one step closer towards a fully functional proof-of-stake system.

Ethereum proof-of-stake chain has upgraded to Shapella. Withdrawal is now enabled

This closes the loop of the original beacon chain design. Validator can deposit -> withdrawal.

— terence.eth (@terencechain) April 12, 2023

The hard fork allows for partial and full withdrawals of staked ETH, which can theoretically unlock 18.1 million ETH when Shapella is forked, currently equating to over $34.8 billion.
However several mechanisms are in place to prevent a flood of the ETH supply from hitting the market, according to the Ethereum Foundation.