People still don't know how to use efficiently LN...

Just an example:

1. Open a 5M sats channel, could be private or public it doesn't matter too much, in the end.
2. Do several swaps through that channel in a total amount of 5 BTC, using many swap services (boltz, loop, fixeedfloat, coinos, zigzag, chainmarket etc)
3. close channel. On the blockchain will be reflected only 5M sats not 5BTC.

Done, you just "wash" 5 BTC.

More examples here:
https://darthcoin.substack.com/p/node-liquidity-guide
https://darthcoin.substack.com/p/lightning-cleaning-machine
https://darthcoin.substack.com/p/lightning-network-submarine-swaps