I don't know if this counts, but I believe Norway taxes unrealized gains (indirectly) via wealth tax. All stock value is on the chopping block come tax time.

I doubt this is a common thing. Whereas the other case (dividends tax credit) is far more common. It impacts those of us in Canada. Our government disincentivizes buybacks and encourages dividends instead. Typically, if you're in a low income bracket, and have investments brewing for decades (with high amounts of unrealized gain) in an unregistered account, it is preferable to get dividends over buybacks.

Denmark is one of them. Germany has something similar. But you can ask your friendly neighbourhood LLM for details on the world's jurisdictions to get a complete list.