Systemd: Redis server wont start when run as a service - too many levels of symbolic links

The unit file is not a symlink, it is a regular file:

-rw-r--r-- 1 root root 1.2K Aug 16 10:32 redis-server.service

You are checking the wrong file. The error message is about the redis.service. Check whether it is a symlink or not.

By the way, the package file list does not mention the redis.service file. Is it there actually? Or maybe you have created it by yourself?

In any case, when systemd refuses to perform 'enable' on a symlink, enabling the unit file by path might work:

$ sudo systemctl enable /lib/systemd/system/redis-server.service

This issue seems to be discussed here https://github.com/systemd/systemd/issues/6318. There is a bug is systemd 232 and it seems to be fixed by changing "ReadWriteDirectories=-/var/run/redis" to "ReadWriteDirectories=-/run/redis" in the unit file.