Unable to Update Sheet Error Message

I just created my first application and shared it with my kids to test it. I tried to make some updates and it said unable to reload sheet. Is there a reason why this is happening? did I do something wrong? Does it switch to a paid account forced option without a notification? I noticed a pro symbol but I havent upgraded yet. I thought that I get a free account up until a certain point, but I am not sure what that point is. Sometime please enlighten me.

This message could be due to the fact that component(s) in your app may use columns that have been removed manually within your Google sheet.

In this case, force the reload of your app on the builder, and it will ask to remove the failing component for you. Or restore the deleted columns in your Google sheet.

Do not hesitate to share screenshots for further help.