Hi JohanAu.
In regards to this issue, the Pipcost should be constant until you stop and restart a strategy when trading live.
I remember I specifically faced this issue when testing the plugin, and the solution I applied was to lock in the the reference exchange rate for the pip cost calculation when the plugin is loaded.
So if you don't restart the strategy the pip cost should be constant.

If you are still facing issue please post your zorro.ini configuration (without the keys) and the asset list you are using and I'll have a look at it.

You can lock in the pipcost in your strategy as a temporary work around until I fix it if this is still a plugin issue.

Cheers
Vince