My Sumsung A70 is displaying a flight mode all the time

Perform a Hard Reboot

If your Samsung phone appears stuck in the Airplane Mode and if it’s not responding, you can start by performing a hard reboot. Don’t worry, this will not affect your personal data.

To hard reboot your Samsung phone, press and hold the Power button and the Volume Down button down simultaneously for more than 7 seconds.

Regards,

Will

You can try these tips:

1. Force Restart Your Samsung Phone
2. Enable Safe Mode
3. Check Update For Your Android OS
4. Reset Network Settings
5. Stop Apps From Changing System Settings
6. Wipe Cache Partition
7. Perform A Factory Reset
8. Contact Samsung Support

I hope any one of the above-mentioned solutions will definitely help you.

Above solutions is refered from here - Samsung Phone Stuck on Airplane Mode? Here Is The Real Fix!

You can find the detailed steps there.

I have the same issue (galaxy s10 lite )sometimes after update sometimes it happens randomly. The fix for me is a lot of hard reboots and restarts . Last time it was after the security update I tried everything and I came to a conclusion that the bug is because some loose connections on the back of the phone because the fix for me was when I punched the back of the phone (light punch) and then restarted it everything was working normally! Next time I'll open the back cover to see if there is any loose connections ! Very annoying Bug !