What are you actually getting when you take a burst of photos? (You'll get a few more than the buffer indicator shows due to streaming to card while still shooting, which depends on how quickly the camera can write to the card of course.)
Possibly a software glitch in the display number that just slipped through. (I know I've never really paid much attention to it on my 7D. 20 something when I have a 'full charge', and will drop quickly during a burst, but then again the 7D's buffer is big enough that you don't really have to think about it unless you're really abusing the shutter button.)
Also possible that they changed how they're doing their processing in camera. Fun quirk of programming is that there are usually several 'efficient' ways to do something, but they may be inefficient in other ways. (Using more memory to process something faster for example)
And then again it could just be that something has gone funky with your camera. I did message a friend of mine who has a 70D, but they seem to be offline for the evening. Hopefully someone else can provide some better help in sorting out what is going on for you.
Canon EOS 7D | EF 28 f/1.8 | EF 85 f/1.8 | EF 70-200 f/4L | EF-S 17-55 | Sigma 150-500