Snapchat has released at least one update a month since you posted that. Are selfie videos in Snapchat still as bad (whatever this means)? I say this because quality is a function of resolution and frame rate. So You need to look for the Snap video file in your Samsung Gallery App, open it, swipe up and read off the details (properties) of that clip.
I use a budget A52 (Snapdragon 720G) and a Snapchat selfie video (with Lens/Filter on) stored in my Gallery has the following resolution: 544 by 960 at 12 fps. On my iPad 9 (2021, A13 bionic), the same Snapchat saves 720 by 1280 videos at 30 fps.
What does it say on your S23 Ultra?