Hi jinkt.
The iPhone problem and the app' trouble may be linked, or not.
Re 2FA - A quick web search indicates that after 2fa is established on iPhone 10, 11, or 12 there is only a 2 week window to disable it. And disabling 2fa may need to be accomplished from your Apple web account. Updating your web account (not sure what this would be) may restart the 2 week 2fa options window. Personally, I would try reaching out to Apple support or a Genius Bar (if that's what they're still called) for help or perspective. Well qualified geek friends who use Apple devices might be able to help as well.
A nuclear option, that may or may not help, would be re-initializing the iPhone (backing up the device to the cloud first, of course). This process can also be time consuming and/or problematic.
Regarding the Tools app' - Were you able to figure out how to clear the app's temporary storage (for Android it's app Cache)? If clearing cache didn't work, were you able to clear the app's critical storage (for Android it's app Storage)? Uninstalling and reinstalling app's may not clear these bits of file/data storage, at least in part because the operating system prefers to minimize effort when reinstalling and re-establishing app's. Residual files/data that are corrupt may prevent app' symptoms from changing or resolving.