When i switch apps a red spot arise from left side of my screen

Greetings washifhossain,

Check and see if the red spot is the Zoom Controller, which may be activating when you're tapping the screen. Check out how to adjust that feature here:

Zoom in on the iPhone screen - Apple Support

"Set up Zoom

1. Go to Settings  > Accessibility > Zoom, then turn on Zoom.
2. Adjust any of the following:

• Follow Focus: Track your selections, the text insertion point, and your typing.
• Smart Typing: Switch to Window Zoom when a keyboard appears.
• Keyboard Shortcuts: Control Zoom using shortcuts on an external keyboard.
• Zoom Controller: Turn the controller on, set controller actions, and adjust the color and opacity."

If unrelated to Zoom, then check and see if other accessibility features have been turned on unexpectedly to help isolate the behavior. You can tap Settings > Accessibility to see the enabled features.

Additionally, ensure your iPhone is updated and test after restarting to further troubleshoot:

• Update your iPhone or iPad - Apple Support
• Restart your iPhone - Apple Support

Let us know if that helps.

Kind regards.

Hi washifhossain,

Thank you for using the Apple Support Communities! To help isolate this issue, can you confirm if this happens when using a specific app? We would also suggest the following article that may help as it contains different icons and symbols on your iPhone:

Status icons and symbols on your iPhone

Hope this helps!

Have a great day.