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Dividends are getting lower not because of the merging but because more and more BFG tokens are getting mined. and the distribution pool stays the same.
You can see a small increase after the monthly burn of BFG tokens.
Actually for example total distributed btc amount has halved from february too. Eth has decreased too. And in the overall i haven't seen any difference in dollar amount, but i am getting paid way more via BNB and TRX now. I am currently mining only with slots even though it's not as steady but you can gamble with trx with quite small amounts and average return to player is quite high.