I’m not saying this is always the right course and of course this doesn’t scale to larger companies, but my first project at my current company a week in was to develop a feature from scratch which ended up involving coding an API for the front end developers, writing an ETL process that used both Redshift (AWS OLAP database), and MySQL designing the schemas, configuring the AWS resources with CloudFormation, setting up queues, messages, lambdas, dealing with the vendor we were integrating with and learning the business vertical. How much longer would it have taken if instead of already knowing their stack - C# WebAPI, MySQL, and AWS - I came from a Java/Mongo/GCP background?
They needed someone useful now to get a feature out that they wanted to charge customers for.
That's why code reviews are a mentoring opportunity. Help your colleague level up.
(Also there should be team dialogue about how to solve some problems more efficiently, I mean, if I was unsure of something I would go and ask colleagues for some guidance, or you would go and do some research on your own)