You can trace it in the chain to see where they come from, in the case of coming from a coinjoin and you want to clean them the easiest way is to use sideswap and perform a pegin in liquid and then a pegout.

The cost will be 0.1% for the pegin and 0.1% for the pegout.

If you have your own Liquid node the pegin is free.

Another way you have is to open a channel with those bitcoins and send it to another wallet (no matter if it is yours or custody) and then make a swap with boltz if you want them onchain.

However if you are going to use them I wouldn't worry about it.