I ran into the same mistake with the described "delayed" and "washed" sounding effect.
It could be, and that was also the case with my setup, that your routing in the interface is not correctly.
First connect headphones to your kemper and check if the delay still persists..
If not...
Try to set the input routing of your interface to stereo.
In my case – i have the Focusrite 18i8 its done via the Focusrite Control Software –
I connected the main outs (left and right) into two separate line inputs (e.g. Channel 5 and 6) of the interface.
In the Software i set the Monitor Routing for my Kemper to be [5-6] instead of routing [5] and [6] separately.
that helped me and now it sounds great with no recognizable delay.
Cheers everybody and stay healthy!
Oliver