You are seeing a yellow warning symbol next to the VAT after publishing your invoice.
QuickBooks Online integrated companies.
This means the VAT is slightly off. QuickBooks Online rounds the figure after publishing which will cause this error.
To bypass this issue, you can enable a setting on your company's Integrate page. This setting allows the VAT amount on the invoice to override the VAT re-calculation to QuickBooks Online.
All you need to do is click the box next to the setting circled in red below, and click Save!