When I update osTicket, I download the ZIP package that contains osTicket.zip and plugins, like auth-ldap.phar.
I copy the files from the upload directory and the plugins to a new folder. So I have the latest versions retrieved from the site. You told me that I didn't have the latest plugin, so I have it by doing this.
We can have a doubt seeing the version of auth-ldap 07/11/2019, we could expect to have something in 2023...
It remains complicated to go from 1.16 to 1.17 with LDAP as your database update procedure is, in my opinion, incomplete and many users have encountered these problems