bcrypt is a good password hashing algorithm. It however needs some additional quirks for long passwords in PHP and should only be used if Argon2id or Argon2i is not available. bcrypt is not available on this system. TYPO3 password storage not only requires bcrypt itself, but also sha384 to be available to use this algorithm. One of these or both are missing. bcrypt is also used as a fallback if Argon2id or Argon2i are not available. Reach out to your hoster to fix these issues and prefer installation of Argon2id or Argon2i.