Vivaldi: the upload/download file windows dialogs do not scale well

I’m using KDE 5.98.0 / Plasma 5.25.5 with a 4K screen, and the global scale is 200%. But this scaling of the dialog does not work well when I want to upload(download) from Vivaldi browser.

As you can see, the UI interface is still very small.

(the upper one is the dialog, while the lower one is what I see opening Dolphin directly.)

How to solve it?

Vivaldi: 5.5.2805.38 (Stable channel) stable (64-bit)

Use the slider towards the right end of your toolbar. I suggest you do your updates cause Framework id 5.99 and Plasma is 5.26 now.