Whatever the last update did, it also added * as a supported link, which means Webnovel will make itself the default app if no other app handles a link.
Go to any webpage in Firefox, and the click on the ... menu and click on Open in App. Assuming the site isn't registered with any other app, it will launch Webnovel, and for certain sites, ask for login credentials.
This is borderline malicious behavior, and needs to be fixed immediately.