We're only a few days in to the current League of Legends PBE cycle, and it seems complaints about Sona have been high. Riot games has announced the changes they'll be making to Sona in Patch 11.16.
Jeevun Sidhu, lead game designer, tweeted an update on Sona after feedback from the community pointed out some issues with spot changes. From Sidhu's perspective, it appears that they are "undervaluing some of the specifics."
Sidhu argues that while there were occasions where two definitive abilities were reported in a late-game group fight, the results also show that it is not likely to occur in normal SoloQ.
"The skill acceleration [of the PBE] is very frontal compared to the current patch [11.15], particularly if the Sona player has a good lane phase," he added. According to Sidhu, we'd need 80 skill acceleration for the old level 11 ultimate to wreak havoc, even with Accelerating.
Riot Games will be removing the AP radius nerf in the next version of League of Legends PBE. The improved Sona will debut in League of Legends Patch 11.16, which will arrive on August 21.