You should be happy that Flash doesn't work anymore.
It's an outdated shit which has more bugs than features.
All big and important websites have already updated to HTML5 which is integrated in the browser itself and doesn't need any sort of plugin.
For the dock,try reinstalling it with:
sudo apt-get install --reinstall dde-dock
Reboot after that look if it's working now.

Could you execute command sudo deepin-feedback-cli and send us the log?
And for the dock issue, it is better if you can send us a gif/mp4 via deepin video recorder.

Hi,

I tried reinstalling the dock but the glitch still stays.

the gif video is below:
https://imgur.com/a/GFSRC

I am not sure about sending the log ... It seems it contains almost all the information about my system setup ... Is there a resource (web page / deepin man page) that would exactly specify what is being sent please? I just want to make sure that I dont send some sensitive data.

Best
Davnov

Dock glitch issue have been recorded and transferred  to our developer.

You can choose deepin Feedback to submit log.