Hi there!
With regards to this issue, it is possible that your iCloud account is really not the acting parent account for your Gmail. I suggest to double check by signing in to your Gmail account via outlook.office.com/mail/
On this page, click on "Your Family" below "Drafts" then click on the "Members" below the "Your Family" title > Click Members, and here you should see the parent account and their full email address. Just login to that parent account to remove the restrictions on your Gmail account first before you remove yourself from the Family group.
Please don't share a screenshot of your email address here in the community as this is a public forum and for your security as well.