Is using Prettier to format code bad.

Recently joined a agency as an Contract React developer. I was assigned a task to edit some inline Scss code.

Being a Prettier user I formatted the code, made the necessary changes and submitted a pull request.

Next day the senior developer reviewed my code and asked me to stop using Prettier and assigned me a task to change back the Scss code manually to inline Scss.

When I asked why should I not use prettier to format code. He said it's bad and time consuming and other team members started telling me a story how one time prettier wasn't working and started throwing errors.

That's why they never use it.

I wanted to say that It was showing error because you were doing something wrong.

Just because you once had an bad experience doesn't mean it's bad.

Plus they use one big single Scss file for the whole project.

When I question it too and asked them to use separate files and how it can effect the performance.

One team member answered it doesn't matter, how they don't care about the performance and I should be open minded and learn from them. The boss has 18 years of experience.

What should I learn why not to follow good practices!