Info Tip Border

I removed some types of info Tip and only displayed thumbnail. The border on the left is redundant.

Please provide more detail, and a screenshot that doesn't crop out most of the info-tip. It's difficult to know what you mean here.

Blank border . . .

Are there any spaces following the {thumbnail} code (either on the same line or underneath it)?

That's the only thing I can think of that could be causing that.

It seems so, but there are still...

This screenshot is from Windows 10 22H2, which is different from Windows 11 24H2.

Again, check for extra spaces in the tooltip definition.

No extra space.

Tried a new instance and it's the same.
Windows 11 22H2
DOpus 13.13.1

After restoring the configuration, it is the same as Windows 11 24H2!