It’s not being “split”, they give a flat 50 € regardless of whether you donate 0 € to them or 1 million €. In fact if more people donate to .world this will, infact, water down the percentage.

If the organisation had a monthly revenue of 1 000 000 € and gave 50 € to them, this would be such a vanishingly small percentage (0.005%) that it could well be argued to be negligible