Coinjoin is not privacy, nothing is hidden, you are just obfuscating ownership even if you do it correctly.
Relatively expensive, tedious, and slow.
Bound by a small subset of users wanting to coinjoin.
Obfuscation degrades over time as outputs are spent.
Liquid doesn't hide sender/receiver, most blocks have 0 transactions so no anon set, and is custodial
Lightning is not private. Especially for receiving. Even LN devs are telling you.
bitcoinmagazine.com/technical/state-of-bitcoin-lightning-network-privacy
Zcash has all the same problems of optional privacy. Novel cryptography. IP isn't hidden. Trusted setup. Dev tax. Going PoS. Blockchain was spam-bloated from 30GB to 260GB in less than a year (lol). Not used on DNMs for a reason.