It's possible to ask Wavebox to open new tabs in the default browser, whilst also setting Wavebox as the default browser, this can be problematic and break the flow of browsing the web.
When Wavebox asks to open a link in the default browser, it has to talk to the operating system (macOS, Windows, Linux) and ask it to open it in whichever app is capable doing so. This process comes with a number of caveats (more info), most of which are down to the way that Wavebox must block an ongoing request, but also in the limited amount of context it is able to pass to the operating system about the request.
Normal tab opening, without involving the default browser.
Normally when you click on a link that asks to open a new tab, Wavebox can handle this all internally and pass all the context along with the request. When it goes to open the new tab, it can make the best decision on how to do this and how to set it up automatically.
Opening a tab in the default browser
When you ask Wavebox to open new tabs in the default browser, but also set it as the default browser, the request has to do a loop through the operating system. Wavebox has all the additional information needed to open the tab automatically, but the operating system only uses some of this when asking Wavebox to open a link.
What does this default browser loop mean?
What does this mean? Wavebox doesn't know where the original link open call came from, nor does it know any of the other context about it, so Wavebox has to ask you want to do and where to open the link.
How do I change it?
The best solution, is to stop opening new tabs in the default browser. You can do this either when prompted in the above dialog, or if you dismissed it, go to Settings > Link Opening and change the setting to Wavebox or new tab
Why can't Wavebox just detect this default browser loop and handle it?
Great question! The short answer is that it can. The problem is that asking Wavebox to open links in the default browser can be a destructive and breaking task, see the caveats knowledge base for more info. By the time that Wavebox has detected the case and done something about it, it's already disrupted the flow of the ongoing request. This means that even though Wavebox will be able to just open the tab as expected, you're still going to fall foul of the caveats.
It's best to tell Wavebox beforehand to handle everything without involving the default browser flow :)