What does "Check background Activity" mean?

[Faith7777]

All day today on my S23 Ultra, when I close recent apps, it shows in the right corner an app is still open. 

However, there isn't an app open. This is the message I get when I tap on it. 

I restart my phone and it goes away but then it returns. 

[SamsungModerator1 · Accepted solution]

Hey there! I would suggest clearing the cache of the device. You can do that by following the below steps.

With the device off, press and hold the Volume Up and Power keys.
When the device turns on and logo displays, release both keys.
Use the Volume keys to highlight wipe cache partition, then press the Power key.
Continue using the Volume and Power keys to confirm your choice if prompted.

If you're still having the same thing happen after clearing the cache then I would back up your device and try a factory data reset to try to reset everything. To do that you can go to Settings, and then tap General management. Swipe to and tap Reset, then tap Factory data reset, and then review the information. When you're ready, swipe to and tap Reset. If you have a security lock set, you will be asked to enter the credentials.

I hope this helps!