Any funds held in your wallet before The Merge will still be accessible after The Merge.
The Merge has been designed to have minimal impact on smart contract and dapp developers, but there are a few small things devs may want to be aware of heading into The Merge.
Not before The Merge, not after The Merge, not ever.
The Beacon ChainThe Merge and the Shanghai upgradeIn order to simplify and maximize focus on a successful transition to proof-of-stake, The Merge upgrade will not include certain anticipated features such as the ability to withdraw staked ETH.