Coinjoins (etc) will provide “forward facing” privacy, meaning that your future transactions with your coins are harder to link to your identity.

The original purchase of KYC’d Bitcoin is still “known” (to the exchange, or government, or whatever), so keep in mind that a KYC’d purchase will effectively be a permanent record that you stacked a certain amount of sats.

That’s okay (usually), but it’s why many people like to build two stacks “side by side”.

Just remember to always keep your two stacks separate (ie separate wallets) so that they never mix.