How can a (forced) PU can lower income ?

[BaronNoir]

I'm trying something with Austria and Hungary, and when I manage to force a PU, the revenu goes way, way, way down, forcing me to disband armies.

 

[SonofWinter]

I'm trying something with Austria and Hungary, and when I manage to force a PU, the revenue goes way, way, way down, forcing me to disband armies.

Were you receiving trade from Hungary before you forced it? Did your trade income disappear, or was it BT? Or was it production? Did some event run out, like a +5% production or a +5% trade. We have no evidence of this having anything to do with a PU.