Been looking at
https://doc.qt.io/qt-6/qtwebengine-debugging.html.
First, might be a good idea to launch dooble with --disable-gpu.
Second, trying to copy something from a web page fails with lots of interesting errors in the console, much in UTF8 unluckily.
Third, trying
set QTWEBENGINE_REMOTE_DEBUGGING=5000
Before launching Dooble gives some response in SeaMonkey at
http://127.0.0.1:5000 but not enough. I saw a console message suggesting using a Chromium based browser, so I also tried with the Qt5 Dooble (use different HOME to use a different profile) and got all sorts of weird errors in the console, much once again in UTF8 I think.
More stuff to consider, the remote debugging could point to a different IP:PORT so someone could try using Chrome on a different OS. See the top link.