The information you received is valid. We're updating the way you sign in to the app starting March 30, 2020. It only affects the iOS mobile app. However, you can still use your Google account when accessing QBO via a web browser. For more details, see the Google sign-in is going away for the QuickBooks Online mobile app for iOS section through this article: Log into QBO With Google.
Also, I recommend using your Intuit Account and resetting your password before March 30. This way, you can use it the next time you sign in to the app. I'll guide you how.
Open a browser.
Log into your QBO company using your Google Account.
Go to the Settings(Gear) icon at the upper right.
Select Intuit Account under Profile.
Click Edit within the User ID, Email address, or Password section.
Aside from entering your login credentials, you can set up a PIN or Touch ID for iOS. This helps you save time when accessing the mobile app. To learn more about this process, visit this article: Use a PIN or Touch ID.
I'm just a comment away if you need further assistance. Enjoy the rest of your day, @chiva-loka19.