The format of encrypted password in `/etc/shadow`

I see a hashed passphrase like the following in /etc/shadow. I don't quite understand its format.

$y$j9T$F5Jx5fExrKuPp53xLKQ..1$X3DX6M94c7o.9agCG9G317fhZg9SqC.5i5rd.RhAtQ7

It is made of four parts as shown below. According to crypt(5), y means yescrypt. https://manpages.debian.org/unstable/libcrypt-dev/crypt.5.en.html

- y
- j9T
- F5Jx5fExrKuPp53xLKQ..1
- X3DX6M94c7o.9agCG9G317fhZg9SqC.5i5rd.RhAtQ7

What is the meaning of the last three parts?