"Waxl dyne untherhouze" bug Every time I start my device a Cleaner window appears. And in the window these words appear: "Waxl dyne untherhouze".

What does that mean? Is there a bug involved?
Sounds like you have malware. Look through your installed apps (from settings) and see if anything sticks out as fake. Uninstall it.

If nothing appears off, then the next step is doing a factory reset. Back up your information first!

If even that doesn't work, call the manufacturer for service. Fixing malware that can survive a factory reset is a very technical and risky process.