Everyone seems to be "worried" about this "tax." This is not a tax. The staff is removing between 20% and 30% of the money in the game. Rather than say "Oh no, I am losing 60 mils I could get a good poke with that!" realize that they are merely increasing the value of your current currency. No one in the game is actually LOSING money, they're just re-assigning what that number means by doing this. How much money you have remains the same in comparison to how much money everyone else had. If you had 500 mil and I had 100 mil, now you have 350 mil and I have 70 mil.
Its like in the old days, were milk and break could be bought for 25 cents. There was not much money in print, so the value represented (not to get overly technical about the economics of this) was a certain amount of gold. As time went on, The amount of dollars in America were increased, but the gold never increased. To accommodate for this, we raised the prices of milk and bread instead of removing some of the money in circulation.
Look at pokemon as the gold, and pokemoney as the dollars. Instead of raising the prices of pokemon, we are lowering the amount of pokemoney in the game. (600 million for a shiny? I remember when I had 25 million and that was the most in the game x5. The next closest person had 5 million. Shinys back then cost 1 million, at the most, and those were mostly common shinys.)
Would you prefer to pay an absurd amount of money for a pokemon? Or would you prefer a shiny that normally costs 10 million to cost 7 million. By doing this, the staff is lowering the prices by 30%. Adjust your prices accordingly and move on.