Your understanding is correct:
Fintech holdings ÷ eUSD Market Cap = (multiplied by 100) → RevShare %
4,242,042 ÷ 24,397,720 = 0.1738 → Multiply by 100 = ~17.4%
Here is the latest proposal which highlights that number shift in Ugly Cash’s percent.
Moreover I think @Mr_Bones has an excellent take and I tend to agree with him. AFAIK its been cheaper for them to swap on base as opposed to mint on mainnet and then bridge to base. Hence why they have been swapping. However, eventually if Ugly Cash continues to grow at the rate they are, there wont be enough eUSD liquidity on Base and they will be forced to mint on mainnet then bridge to Base. Here is Ugly Cash’s largest wallet(on base): DeBank | Your go-to portfolio tracker for Ethereum and EVM