lento4kaUA Please clear the EA App's cache:
https://help.ea.com/en-us/help/faq/clear-cache-to-fix-problems-with-your-games/
and repair the game (EA App > Sims 4 > Manage > Repair). Then, before trying to play, set exceptions for TS4_x64, TS4_DX9_x64, and TS4_Launcher_x64, or the entire Bin folder they're in. Set an exception for EADesktop.exe as well.
If this doesn't help, disable your antivirus, temporarily of course, and repair the game again. Then test without the antivirus running. As long as you don't do anything else at the same time, your computer should be safe. If the problem is gone, reenable the AV and set the exceptions above.
If you still get the error, please try the other suggestions in the first post of this thread, which is for a different but related error:
[CURRENT ISSUE] Sims 4 already running | EA Forums - 11818313