It's an issue if you're exchanging fiat for bitcoin at regulated exchanges. Meaning if you're accepting it for goods and services, it's not. If you're using KYC-free markets (such as bisq, peach, robosats, hodl hodl, etc) it's generally not (in lieu of opsec fails) it's not. And if you're mining, it's not. Coinjoins, lightning swaps, and subswaps do generally make it less of an issue if you've bought kyc but there's always the record that you had some, and the more that is the harder that is to obfuscate with any plausible deniability. Nobody thinks you donated 50 BTC anonymously. Not that there's anything illegal about failing to declare capital losses on coins purchased kyc and sold on a p2p market...