This idea is one that has roots going back a long way.
The premise is that Google will not assign as much value to the
content that is sitting behind a tab or accordion.
For example, text that is not viewable on the first load of a page.
Google has again debunked this myth as recent as March 31, 2020,
but it has been a contentious idea amongst many SEOs years.
In September 2018, Gary Illyes, Webmaster Trends Analyst at
Google, answered a tweet thread about using tabs to display
content.
His response:
“AFAIK, nothing’s changed here, Bill: we index the content, its weight
is fully considered for ranking, but it might not get bolded in the
snippets. It’s another, more technical question how that content is
surfaced by the site. Indexing does have limitations.”
If the content is visible in the HTML, there is no reason to assume
that it is being devalued just because it is not apparent to the user
on the first load of the page.
- Tabbed Content Affects Rankings
HOW TO SPOT SEO MYTHS: 20 COMMON SEO MYTHS, DEBUNKED