When it comes to Bitcoin, SHA-3 is not used. Instead, Bitcoin uses a different hashing algorithm known as SHA-256. While SHA-3 has many benefits over SHA-256, it is not used by Bitcoin for a few reasons. First, SHA-3 was only finalized in 2015, while Bitcoin was created in 2009.
Second, SHA-3 is not as widely adopted as SHA-256, so it would be difficult to switch to using SHA-3 without causing major disruptions. Finally, SHA-256 is considered to be more secure than SHA-3, so there is no need to switch to using the newer algorithm.