How does corrupting an item with a new implicit affect life pool

Hi, have a normal cloak of flame and a pool of 6315 life. When I replace it with another cloak of flame with '5% increased maximum life' corrupted implicit I end up with 6100 life. What is going on? Is it just some random corruption thing?

Just me being thick, I had the life mastery for no life mods!

check if you have the mastery for increased life if the body armour has no life tag as the corruption will disable that.

Yes as above stated, you do have that mastery on your tree, so it may not be the best combination. There are some items in the game that interact with corrupted modifiers in certain ways, eg. Shadowstich, but I think the mostly likely reason in this case is what the above poster has replied. Probably no corruption or a different corruption will be better in this case than removing the mastery point, unless you have a good use for the extra skill point.