permission denied while uploading in arduino on ubuntu

https://askubuntu.com/questions/1261380/error-in-recognizing-arduino-on-ubuntu-20-04

This happens because your user account does not have permission to access the USB Serial port.
You can fix this by running sudo usermod -a -G dialout $USER and rebooting your computer. After this, start Arduino IDE again, choose the port again and upload the firmware again.
Note: In general, I recommend installing the "Arduino IDE" Snap from Ubuntu Software instead of installing Arduino IDE manually from the Arduino website. The snap should check if you have the right permissions and explains how to fix the issue.