Yes, I can also confirm that renaming to bbpress.min.css brings back the styles.
Same problem. I changed the CSS on my forum about a year ago, uploading the custom styles to Active Theme > css > bbpress.css
Then upon this latest update, they all reverted back.
It is fixed when you copy/paste the CSS code from that file into either main style.css or the Appearance > Customize > Additional CSS
I also use Autoptimize which wraps the bbpress.css code into one file.
I would like to know what’s causing the issue even though this is a workaround.
