Before the Shanghai upgrade, ETH stolen withdrawals are being processed by Ethereum Goerli Testnet.
Coinbase stated that it anticipates that demand for ETH unstaking will surge following the Shanghai upgrade.
However, the exchange stated that processing ETH unstaking requests could take several weeks or even months.

Ethereum developers have set a target date of April 12, 2023, for the long-awaited Shanghai upgrade during the “All Core Developers Execution Layer #157 call” held on Thursday. The processing of stale ETH withdrawals has already begun on Ethereum Goerli Testnet in advance of the Shanghai upgrade.

There has been a lot anticipation about the Shanghan upgrade among ETH holders who have had their ETH tokens held up since Ethereum announced plans for the Merge Upgrade that would transform it from a proof of work (PoW), to a Proof-of-stake(PoS), blockchain. Coinbase anticipates that the Shanghai upgrade will increase ETH unstaking demand.

It can take weeks or even months to complete difficult requests

Coinbase claims that it could take up to weeks or months for ETH unstaking requests to be processed on its platform. Coinbase will not process the unstaking process. Staking requests can be processed on-chain. Coinbase will not act as a channel for users to receive unstaked Eth once the tokens have been released.

7/ We expect that unstaking will be in high demand soon after the upgrade. It may take weeks or months for the protocol to process unstaking requests.

— Coinbase (@coinbase) March 15, 2023

Coinbase was able, with the Merge upgrade, to allow users to stake Ethereum on their platforms without being able to withdraw the staked tokens.

After April 12, holders of ETH on platforms such as Coinbase will have the ability to withdraw their staked Ether and continue to stake more ETH, without having to be subject to an indefinite lockup.

After the Shanghai upgrade, Coinbase users can now unstake their Ethereum.