Dangerous to use if you're not careful. I guess that is one of the many downfalls of not having secure defaults. Taproot and Schnorr are slowly coming to bitcoin. But would this blog post even exist if they had used a coinjoin/payjoin or lightning?
It is essentially certain that strong privacy will never come to bitcoin. Taproot and schnorr will make no meaningful difference, unless you mean it will assist people in doing atomic swaps to a private currency like Monero. Average people will never make the effort to do expensive (or cheap) coinjoins that will make them look suspicious. Lightning network does not have strong privacy guarantees and it continues to struggle to gain adoption, safety and usability.
I may, perhaps, lack imagination, but I really can't fathom how privacy comes to a system where the fundamental artifact of creation is an ever-growing record of every transaction.
It seems like the kernel of Bitcoin is maximally open information, not secrecy. Obfuscation of transaction is possible, but any solution that could actually hide transaction information would be incompatible with the trust model that Bitcoin is based on.
In fact the US government put out a bounty to trace monero transactions just after Ciphertrace made such claim, and ciphertrace failed to win the bounty, so it appears to be ineffective
