The civic Redistribution currently has "-50% from Trade Routes, and +1G from Camp, Mine".
If I am not wrong, this -50% is being applied as an integer round down to the calculation of the total yield, which already internally uses an integer round down.
So, I read, for example, without Redistribution, in a city of size 14:
2.30 base profit
+50% for harbour
+20% for population
+25% for connection to capital
the gross trade of 2.30 * 1.95 = 4.485 becomes floor[4.485] = 4.
With Redistribution, the 4 becomes 2. Similarly, 3 -> 1, and I'm not sure whether 1->0. In an extreme case, a gross trade of 3.99 becomes floor[floor[3.99]/2] = 1.
I presume that the intention was to instead embed the calculation:
2.30 base profit
+50% for harbour
+20% for population
+25% for connection to capital
-50% for Redistribution
the gross trade of 2.30 * 1.45 = 3.335 becomes floor[3.335] = 3.
As it is now, the effect is very strong. Only in the earliest part of the game are there possibly enough Camps and Mines to be able to compete with it and make the civic worthwhile. At some point, it is worth reverting to Reciprocity, and it's a long time before any other possibilities become available.
If it's not possible to embed the calculation, the "-50%" could be replaced with "1 less gold, with a minimum of 1", so max[floor[gross]-1, 1].