In the Advanced properties... under Taskbar, there is an option for 'Blur' for the Taskbar transparency mode:
Originally I was going to post that this Blur option didn't work, but then I read in this other thread that suggested Start10 might be needed. I installed Start10, and sure enough, the blur started to work. I also tested this out in a VM with Win10 x64 2004, and got the identical results. Is this expected?
Without Start10 (disable/stopping the Stardock Start10 service and sign out/back in is enough to stop it from working) :
Like the other thread suggested, the options for Start10's taskbar don't seem to make much difference with Curtains enabled but Curtains doesn't seem to have all the Start10 options like the amount of transparency. Are more options for that coming or are we stuck with the Windows default acrylic blur?
As a sidenote, Basj's Simplic Mod Curtains is really quite a nice style to try, and inspired me to tweak the Midnight theme taskbar with some transparency on my own, with this rather aesthetically pleasing result: