Screen lock doesn't activate on my iPhone while using Instagram

Settings > Privacy and Settings > Camera [All the apps that have access to Camera will lock only after the app is closed.

Other apps have their own settings that might affect the screen lock behavior. Check within the app settings to see if there's an option related to screen lock or device sleep.

I find this issue a complete security issue that Apple should address immediately. I am new to the iPhone 15 pro max and with how locked down Apple is, I am surprised such a huge issue as such exists. What would be able to do such… the apps themselves or is it an iPhone software issue?