P: Moving layer leaves duplicate/shadow image

Yeah, but how confident are you that the issues with the modern Compositing Engine that made it necessary for some users to use Legacy Compositing in the first place have been addressed?  
The Layers Styles on Groups issue does not seem to apply anymore but if I remember correctly there were also issues with some Blend Mode combinations (possibly also in connection with Groups ... not sure anymore). 

Thanks. Will have engineering take a look. The workaround is to make sure "Legacy Compositing" under Preferences > Performance is unchecked. (Note: It's unchecked by default)