This is a known issue, but it’s actually good news for you.
This error is Google doing the 'right' thing, as they prevent people from using **in-app browsers (in particular Instagram/Facebook’s built-in browser when clicking directly on the ads, etc.). These browsers implement non-standard methods to track user activity on websites opened in-app, and they are NOT private.
The solution? Navigate to https://app.timeleft.com using a standard Safari/Chrome/Edge browser. You will be using a more secure browser, and Google will not block it.
We assure you this is due to Instagram's choices to attempt to track user behavior via their in-app browser, and not any lack of security-consciousness on our part.