It’s not just you. I have difficulty distinguishing between the two very similar greys since the recent update. I’ll flag it up to one Web developer and see whether there’s anything he can do.
When the Forum moved to Discourse a few years ago I found much of the styling unsatisfactory, so I went to town with some custom browser styles. To begin with, I changed the font size. Everything I’ve clicked on is now a pale grey, while the threads I’m especially interested in are green, and the long-lived ones I don’t want to see get a grey background.
It needs updating a couple of times a year, but it works well enough for me.