Hi @Anderstone, thanks for your post. At the moment it is not possible to link the back button to a certain tab natively.
Here is a post that may help, which talks about linking to a specific tab: https://discourse.webflow.com/t/linking-to-specific-tab-from-another-link-or-button/3665
The back button is a browser feature, when it is used the page reloads the tab in it’s original state and shows the default tab.
I hope this helps to give you some ideas, it might be possible to do this somehow using javascript or to create links on your portfolio pages that direct a user to an anchor point on the original page, for example, on the original page you are linking back to, create an id in element settings for the element that should load with focus, lets say the element id is “section-tab” then the link to that anchor point would be something like https://www.mysite.com/page-name#section-tab
See how to set anchor links here: https://university.webflow.com/article/anchor-links
I hope this helps