Bottom 5 maybe, definitely not top 5. The only time people thought she was legit top 5 was almost a year and a half ago.
- still has 950 health which is a handicap for no reason - still an overreaction in my opinion when everyone thought she was #1 when the game first came out (at the time the meta wasn't fully evolved and over time, I think Sonya would've still been good but definitely not in the top 5)
- easily mashed on because her good options start with a high and she has no good mids or lows to check with (too slow, punishable, or no range)
- her low starter b3 string to check opponents is full of FB gaps and is interruptible unlike Johnny's b34 for example
- way too many counterzoning options in this game to make her zoning any decent (it does work in some MUs but you have to basically drop zoning in a lot of MUs which is one of her only real strengths) - the game is very antizoning in general
- doesn't have good customs and didn't receive a boost like many other characters (also characters like Kano and Frost jumped ahead of her on the tier list with customs and hitbox fixes)
- has lots of bad MUs and isn't very viable competitively in my opinion, it'll be tough going 100% Sonya (there's a reason Scar dropped her for Kung Lao a long time ago - a lot of her bad MUs are also against common tournament characters)
In my opinion she's dropped down further in the tier list with Ultimate. She was a mid tier character in Aftermath but now with customs and her not receiving any significant changes, other characters she used to be better than are now ahead of her. Most other characters in this game are autopilot and have way too many good options. I wouldn't be surprised if she'll end up being in the bottom 5 in most top player's tier lists going forward. She already was in a lot of top player's tier lists for Aftermath like Rewind, Kombat, Avirk, etc.
In my opinion Cetrion, Shang, Cassie, Fujin, Jacqui, Jade, Liu, Scorpion, Sindel, Mileena, Erron, Sub, Johnny, and Joker are all bad MUs. They either outzone her, eliminate her zoning options, or have 7f jabs to punish most of her options like her amp ring or b3. There might be a few others like Frost, Kitana, Lao, and Geras but I've had them at even for now. She's become pigeonholed to be a zoner in a very antizoning game.