Why is my car is getting code p2191?

The first thing I always do is get a scan to see where it lies—maybe it's clear-cut once you can see the B and C codes that generic scanners always seem to miss. That said, if the code isn't very clear and you checked on a good all-systems scanner, disconnect the MAF sensor and drive the car around for 5-10 minutes. Always use a known path where you KNOW how it behaves without issues (example: a Rec center where one can fly a drone in an open field), so you can bail once you know it's good, should it act up from being "flooded" with fuel. It will consume more fuel because the car isn't "optimizing" its fuel use, but the default mapping provides a solid base to rule out a deeper issue. That said, without knowing the year of your Sonata, I can't tell you WHERE it is, but always look near the air filter box under the hood. If it seems rough, find a place to park and unplug the oxygen sensor. This could mess up how it handles if the car does not have a default mapping, so take it around the lot briefly to be sure. The MAF always has a default "safe" map in the ECU as a backup.

If the engine "floods" with fuel, find a parking lot, plug the MAF back in, and then let it reset and burn the built-up fuel for 3-5 minutes. Depending on how it behaved, disconnect it again and get it home. You now know if the MAF is bad or not.

If you clean it or replace it is your call - the MAF is so cheap with nearly every manufactuer unless it's visibly dirty it's just better to replace them long term - cleaning it can help buy you time to order one.

If it still occurs with those parts disconnected (and the PCV valve is good, or you replaced it earlier), check for loose hoses, cracked rubber hoses, and any cracked plastic in the engine bay, like air filter boxes. If it all looks good, then it could be clogged fuel injectors - especially on the GDI engines. Get something like Techron and drive the car on a highway at the normal speeds, but ideally go for 60-70mph with variations on the loaded RPM - the idea here is you want to get the gas with cleaner in the injectors and engine, and driving it somewhat hard helps clear things like the injectors. This doesn't always work when they are heavily clogged, but with a minor clog, doing an Italian tune-up can help unclog things, even on a GDI engine. Italian tuneups on GDI engines are not effective when it's in the intake valve (you have to get it cleaned by taking the intake off and using a chemical solution or "sandblasting" it out with walnut shells) unless you can get a cleaner that targets the intake valves, but injectors and pistons (and subsequently, the upper heads of the engine) still benefit.