I just noticed that the problem happens when I try to type the url.
For example if I type ‘/’ which is my pwa home page, the start_url is set to false. If I type “nico.html” and there is no page named “nico” then I would get start_url set to false as well.
Only when I type or select a page that is inside the design file, the start_url is set to that page. This is a bit problematic because I use Bootstrap Studio to build my frontend and NodeJS to serve it (backend). I usually use urls like ‘/’ or ‘/account’ rather than the HTML file name.