@ekinkilinc If you use mods, try moving your entire Mods folder to the desktop; delete localthumbcache.package as well. Then test your save. You don't need to save your progress, so don't worry about any missing content.
If you don't use mods or custom content, or you do but the above doesn't make a difference, please repair the game in Origin: open your game library, right-click on the Sims 4 icon, and select Repair.
@ekinkilinc Try playing in a completely clean user folder. Move your entire Sims 4 folder out of Documents\Electronic Arts and onto your desktop, and when you launch the game, a clean folder will spawn with no content. Don't add anything to it yet; just start a new save and see whether you still have the same issues. It would help to have the new sim or sims do the same things that are generating the blank notifications in your current save.