I had forgotten that that tag even exist to be honest.It seems like you forgot to do so for all worker builds
I added <bCanRemoveWithNoProductionGain>1</bCanRemoveWithNoProductionGain> to young forests if other forests had this in worker builds.
Committed that to release now.
Just make sure that builds/improvements that are unlocked before slash and burn doesn't have that tag, as it would allow you to remove forest before slash and burn tech.