Where does `date` get the system timezone from?

I always thought Linux systems used */etc/timezone* for the timezone, but:

$ cat /etc/timezone 
Etc/UTC
$ date
Tue May 28 12:34:01 PM PDT 2024

Here, the */etc/timezone* is UTC but date is reporting in PDT. How is date determining the timezone? This is Ubuntu 22.04, if it matters.