Sakura doesn't know why Sasuke ended up in the hospital again. She simply knows something's changed.
Disclaimer - I don't own Naruto. This was written for the Jutsu theme for SasuSaku Month 2021.
One of the things I didn't get to touch upon is why Sasuke is acting the way he is in this - it remains an unknown for both Sakura and Naruto. On top of Sasuke listening to Kakashi on revenge, he'd told the Sound Four no which they didn't like. The result of him not looking for revenge anymore is some of his old personality coming out, yet he also never properly dealt with his grief. (7/6 on AO3)