On the normal Roblox site in Google Chrome on Windows 10 (might happen on other browsers and operating systems,) if you open multiple tabs of people and one of them has sent you a friend request, then accepting it makes it say ‘Unfriend’ on the rest of the tabs even though you aren’t friends with some of them. Expected behavior would not be showing the ‘Unfriend’ button on pages of people that you aren’t even friends with, but refreshing makes it work as expected again.
I was able to get this to happen 3/3 times and I tested it without any Roblox enhancement plugins enabled. Not sure when it started happening, but since I rarely accept friend requests I just noticed it today.