it is more correct to talk about the "pseudo-anonymity" of most cryptocurrencies.
the basic principle of the blockchain is transparency and publicity of transactions. The chain of operations of any member of the network can be tracked and determined, for example, the frequency and volume of transfers. The system also provides any user with the ability to write out the addresses from which the amounts were transferred; each of them can be used for a new search. And if the owner left his data somewhere - for example, when ordering in an online store or on a forum - you can also establish his identity.
To maintain anonymity, it is important not to leave any information on the Internet, which is very difficult ..