Look for the toggle in Settings > Animations > Messages.
A recent WhatsApp update has introduced animations for messages – when you receive a message, it expands into place rather than just appearing on the screen. (It reminds me of the “Scale” effect for window minimisation on macOS.)
I find it distracting and it makes one of my friends dizzy, so I found the setting to turn it off:
- Select my head in the lower right hand corner to open the settings
- Select Appearance
- Select Animations
- Toggle off Messages
When toggled off, messages just appear at full size immediately, rather than animating in.
These steps are for the iPhone app. I assume a similar toggle exists in the Android app, but I haven’t checked.