When Contribution Page has no labels (just amounts) -> the Review and Thank you and Receipt all show string - null in ESR 5.27.4 AND dmaster [Regression]
Upgrading from 5.21.3 (previous ESR) to 5.27.4 (current ESR)
Hit Review your Contribution button
null is visible on Review, Thank you and Receipt.
Quick solution: hide label with CSS
To upload designs, you'll need to enable LFS. More information