> Is also possible to snapshot individual wallet balances, addresses, transactions?

Unless the wallet is a routing node I don't think this is feasible for third parties to do. But all wallets are connected to at least one routing node, and each of those routing nodes know the balance of your channel with them. Some, like Binance's routing node, also proactively state in their privacy policy that they log this data and share it with law enforcement, including info about any transactions that flow through their node. So be careful who you open channels with.

> So not an unsolved problem anymore?

I'm not sure. The solution is known but I am not sure node devs will upgrade to versions that don't support payment probing. It's a popular feature with native commands for it in LND and Eclair, and they would have to disable that popular feature that many wallets rely on to assess the likelihood of a successful payment before attempting one. It seems unlikely that LND and Eclair will upgrade to a version that disables this. Maybe a new, privacy focused lightning network subnet is what's needed, where participating nodes all announce that they won't allow payment probing.