In short
Text placed below an image works better in onboarding because people read from top to bottom and images catch the eye first. The image-then-text order holds attention, reduces cognitive load and makes the text read as a natural extension of the visual. The image must also match the meaning of the text, or it causes mental strain.

Here’s why placing text below an image is more effective for user engagement and reducing cognitive load during onboarding👇:
🤓 User attention and motivation are limited resources. Try not to waste them—you still have to show them the paywall!
P.S. It's essential that the image aligns with the meaning of the text. This reduces cognitive load and enhances comprehension. When there’s a mismatch, the isolation effect may attract attention, but it also causes mental strain and disrupts understanding.