It is not up to Apple to find a solution for your issue with a third party app not working.
First try a forced restart, if that doesn't work reinstall the app. If that doesn't work contact the app developer for help with their software.
Also, if you are using a VPN, delete it, don't just disable it.
Try a forced restart.
• Press and quickly release the volume up button
• Press and quickly release the volume down button
• Press and hold the side button.
• When the Apple logo appears, release the button.
Force restart iPhone - Apple Support (IN) https://support.apple.com/en-in/guide/iphone/iph8903c3ee6/ios
You will need to continue to work with Instagram if the previous suggestions don't help.
Here is a link to their help page.
https://help.instagram.com/