It's a pretty solid sign of an inexperienced developer when they think UTC needs to always be listed as the timezone. Most people with more experience know that if there's no timezone attached it should always be populated in, and assumed to already be in, UTC.
That said, it's rarely mentioned, which is a problem. And as the parent comment mentions, there are valid cases for tracking things in local timezones to retain user-local consistency.
There's a long history of databases using a client-controlled timezone per connection (which defaults to the server's local timezone) and storing only local time. I wouldn't rely on seeing UTC unless the team is very careful about migrating legacy data and consistently using TIMESTAMP WITH TIME ZONE columns and functions.
That said, it's rarely mentioned, which is a problem. And as the parent comment mentions, there are valid cases for tracking things in local timezones to retain user-local consistency.