So each Bitcoin in the Eco-system today isn't equal. Some Bitcoins were used in a crime , and if they were , they can be worth less because of the transactions that have been facilitated with that specific Bitcoin. And if there was a crime that happened 20 transactions ago , and you now have that specific Bitcoin , can you be indicted for a crime that someone else has committed but you are holding the Bitcoin that is associated with it?
If this is the case , how can we consider at this point , BTC as a store of value?
fungibility is an issue for all forms of money, not just BTC. if you buy forged/discounted black market gold, it needs to be melted down and re-stamped before passing as legitimate. if you receive marked, serialized bills in a ransom operation or bank robbery, they can't be deposited at banks or easily spent.
on-chain tumbling can be effective at obfuscating the source of funds and making outputs fungible again. however it's important to note that mixers and coinjoins can be retrospectively broken as new privacy vulnerabilities are discovered.