Talking about keys, I've seen the new trend of CEX like Binance,Butget and OKX incorporating seeming decentralized wallets into their deliverables and those wallets have keys, just like Reputable decentralized wallets too. I would love to warn anyone who surely loves his coins not to in any way preserve his coins in CEX wallets, Do not be deceived, they have control over your coins if you leave it in their wallets.
It is advisable to use Reputable ones which are open source like Electrum, Blue wallet e.tc to have more controls over your coins. Anything from CEX is not decentralized, no matter how they paint their story, BE WISE.
There are many cases where centralised exchanges have seized accounts of users for different reasons like not doing KYC etc. If you have your coins in centralised exchange then there are bright chances that you may be stripped off from your coins without any reason, notice and warning.
Storing your coins in decentralised wallet should be the prime rule which all of us must follow. It's not very difficult to secure your decentralised wallet if you have done basic measures like not securing your seed online. The real advantage of securing your coins in decentralised wallet is that even if you access them after years they will be there. You are the boss of your coins only if they are in your decentralised wallet. Happens with me, I forgot I have bitcoins in my wallet but once I access my wallet after a gap of months I found them as it is. I don't think that will be the case if I have stored my wallets in centralised exchange.
It is true that storing coins on centralized exchanges carries a lot of risk. Exchange rules and KYC requirements can change, and your account can be closed or your funds frozen for any reason. This is a big concern for many users.
However, storing coins through decentralized wallets is actually much safer and you have full control over it. By keeping your wallet seed phrase and pass secure, your funds are completely safe, and you can access your coins at any time, even after many years. This is much safer and more reliable than on an exchange.
However, if you ever lose/forget your seed phrase and pass, your funds will be completely frozen. Or if someone else knows your seed phrase and pass, they can take all your funds without your knowledge. So always keep your seed phrase and pass private, and keep it safe, so that your funds will be safe forever.
I write down my seed phrase and pass in a diary, and keep it in one of my lockers, and only I have the key to it, and no one knows where my seed phrase and pass are, not even my family. This keeps my funds very safe.