Something I noticed just now (look inside the circle):
The badge with the bounty amount in a bounty notice was previously white text on a blue background; now it has the same colours as the notice behind it. Given that the badge text is still visibly offset relative to the baseline as before, this doesn’t look like an intentional decision to remove formatting.
(Another bug I noticed is already covered at Green reputation badges on Summary page have black text, so I edited that part out.)
Clearing the cache did not help.