Finder View Action Button

I don't have an answer for your different Big Sur platform UI discrepancies unless it is somehow detecting Desktop and laptop screen dimensions/resolution and basing icon provisioning on that factor. My 2014 MacBook Air running Big Sur has the second UI example that you have shown. And until my M1 mini gets here, I don't have a desktop Mac capable of running Big Sur.

Apple revised the Finder UI once again for Big Sur, and you no longer have access to the four-item list view icons in the Finder window toolbar. And you cannot replace it from Finder customizations either. Use ⌘+1 thru 4 to enable these views via keyboard shortcuts in Big Sur.

You are welcome. Hopefully, the answer to this question will materialize.