Don’t blindly trust opinions found on the internet.
Comparing password (random character strings) and passphrases (random word sequences) can be like comparing apples and oranges. The relative strength of each depends on the number of characters and size of the character set (for passwords) or on the number of words and size of the dictionary (for passphrases).
Using Bitwarden’s password generator with settings that maximize complexity, a 14-character password would have an entropy (strength) of approximately 86 bits. For a passphrase to have comparable strength, it would need to contain 6–7 random words (corresponding to 76–90 bits of entropy). A 5-word passphrase (even with numbers and special characters added) will not be as strong as a random 14-character password.
The benefit of using passwords is that for a given strength (entropy), it is more compact (approximately 25% the length of a comparably strong passphrase). The benefit of using a passphrase is that for a given strength (entropy), it is easier to memorize and to manually type (and to communicate verbally).
Thus, you should generally use passphrases only when they secret has to be memorized or manually typed (or verbally communicated), and use random-string passwords for everything else. For this reason, it is recommended that your Bitwarden account password should be a random passphrase consisting of at least 4 words.
Furhtermore, please note that the required length (number of characters or number of words) will depend on what type of hashing or KDF algorithm is used during the authorization/decryption process. Bitwarden vault passwords are generally considered sufficiently strong with only 50 bits of entropy, because Bitwarden’s authorization/decryption processes uses a very slow KDF algorithm (which increases cracking resistance).
I’m not that familiar with SSH, so @Quexten (or somebody else) can correct me if I’m wrong. However, I think that the idea with Bitwarden’s SSH agent is that it directly [signs the authentication challenge with] provides* the SSH key when logging in to the server, no passphrase required. You could (should!) use a passphrase as the master password for your Bitwarden account, but once your Bitwarden app has been logged in and unlocked, then only the SSH key is used, not a second passphrase.
*Edited to correct the original inaccurate description of SSH authentication.