The driver is the price of oil making status quo untenable. The retroactive business isn't a serious suggestion and thus won't ultimately be punitive. Rather, its an argument used to reframe/challenge the framework in which 2019 transfers occurred (1) https://twitter.com/wrodgers2/status/1254444597033517058

Prior framework was "$380m not contingent on oil transfer to SOMO, but rest of the budget allocation is (hence KRG 'only' getting $380m/month)" (2)

My guess is retroactive argument is meant to challenge that framework, and thus delegitimize legal rationale for ongoing transfers. I expect it is read as such by KRG (ie, no one expects any effort to recoup that $) (3)

All of this is also laying groundwork for the negotiations on what the next chapter of KRG-GoI energy and econ coordination will look like. You always show up with the list of stuff the other party owes you for (4)