One possible solution to this problem is to check your device's Accessibility settings to ensure that Assistive Touch is configured correctly. Go to Settings > Accessibility > Touch > AssistiveTouch. Make sure that AssistiveTouch is turned on and configured properly. You can customize AssistiveTouch to your preferences, but ensure that it's enabled for the functionality you need, such as app downloads and payments.
If the issue persists, you can try resetting all settings on your iPhone. This won't delete any data but will reset all settings, including Accessibility settings. Go to Settings > General > Reset > Reset All Settings. After the reset, you'll need to reconfigure your settings, including AssistiveTouch.
Additionally, ensure that your iPhone is running the latest version of iOS. Sometimes, software updates contain bug fixes and improvements that can resolve issues related to Accessibility features like AssistiveTouch.
If the problem continues despite trying these steps, consider reaching out to Official Apple Support for further assistance. They can provide personalized guidance and help you troubleshoot the issue in more detail.