Meanwhile, Sona's "buffs" in 5.3...

Yup. Because Sona is an unfun champion with no relevant Counter play. Ok.

"buff" i don't think you know what that word means

We buff sona so that we can sell her skin. Don't worry. We'll nerf her in the next patch. It's already on PBE.

Even though it's not what they said, it does suck.

They weren't buffs, they were her unchanged stats BEFORE they did the changes. So it's a bug because it wasn't meant to return to the previous stats.