Board Thread:Support Requests - Getting Technical/@comment-46036441-20201023123213/@comment-1038387-20201023140801

Tabview isn't enabled by default on UCP, and is definitely not coming back.

Tabbed content in general is incedibly not recommended, a tab inside a tab is kill it with fire. The mobile performance is so bad it tanks your SEO. See this Best Practices blog for some ideas on organizing content.