https://bugs.winehq.org/show_bug.cgi?id=41273
--- Comment #2 from Alexandre Julliard julliard@winehq.org --- (In reply to Austin English from comment #1)
I've noticed similar results with Firefox under wine and XFCE mousepad. Copying to notepad then to mousepad seemed to work for me, but I didn't investigate that very much.
Could you run a regression test?
My guess would be that it's 42c221db6c61966486344fb65231ae35d9f4ea49. There are a number of things in the X11 clipboard support that will need to be rewritten before this can work correctly again.