Adriaan Dekker and Arpan Banerjee just caught a slight update related to sitelinks within video ads on YouTube desktop.
If sitelinks don’t fit within the available space, a scroll bar now appears, a behavior not seen before.
Here’s how it looked like before without scroll bar when sitelinks were first spotted on desktop in March 2025:

Here’s what it looks like now:

In case you missed the earlier tests:
- YouTube Ads Now Support Sitelinks on Desktop
- YouTube Introduces Half-Screen Video Ads with Scrollable Sitelinks
- Sitelink Layout Experiment on YouTube