You need, SET KAI_AUTOMODE=DART in your config.sys, the SET command puts it in your environment. It is actually for libkai, to quote, "K Audio Interface v2.1.0. DART/UNIAUD implementation library." it can use DART or Uniaud but the Uniaud support is broken.
The browser itself seems to be awfully memory hungry. Might help to SET QTWEBENGINE_CHROMIUM_FLAGS=--single-process.
As for needing to use incognito mode, sounds like your profile is damaged. Delete the files in home,
".local/share/QtExamples/simplebrowser/QtWebEngine" and ".cache/QtExamples/simplebrowser/QtWebEngine". Without the quotes, home is usually in your boot disk under x:\home.