Substantial renewable energy (RE) cost reductions have raised the prospect of a RE subsidy-free era of the energy transition. The envisaged policy cornerstones of this era are carbon markets, which create economic incentives for sustaining further RE deployment. However, this overlooks that exposing RE to market risks and rising general interest rates would result in substantially higher financing cost, which in turn lead to much steeper carbon price paths. The resulting political pressure may provoke a price-depressing regulatory intervention, disrupting further RE expansion. Here, we conceptualize this feedback and infer indicators for the risk of such an intervention. Quantifying these indicators for the European Union, we find that increased financing cost could double carbon prices in the long-term, half the rate of renewable capacity deployment in the next 15 years, and considerably increase fossil fuel plants' profits. This implies a substantial risk of pushback that policy makers should safeguard against.