Designer 1.9.0.791 on Windows 10 2004.
I searched in the “Designer Bugs found on Windows” and “Designer Beta on Windows“ forums for “paste style” (without the quotes) but couldn’t find this as being reported.
In version 1.8.5.703, I can copy the style of a layer and then paste it onto another layer using Paste Style and all is okay.
However, in 1.9.0.791, when I use Paste Style the Stroke formatting is not applied.
See attached video where the first half is what I expect in the current commercial release and the second half is what I get in the latest beta.
2020-10-19_12-48-18.mp4