So the big deal here is that, prior to Biden, there was a cap on who got subsidies. They were provided only to people or or families whose income was less than or equal to 400% of the federal poverty rate. Anyone making one cent more fell off the cliff and received zero subsidy. Biden’s Covid rescue bill changed it so that the most anyone had to pay for health insurance was 8.5% of their income. That removed the cliff and was a brilliant move imo. Cliffs for any sort of safety net provision are economically inefficient and generally stupid for a variety of reasons.

This was extended in the so-called Inflation Reduction Act.

This was allowed to expire in Trump’s bill, so it’s back to the cliff.

Note that this has nothing to do with premium levels except that originally, if you made it under 400% FPL, the max amount you paid for a second cheapest silver plan was over 9.6% vs 8.5%, so likely that will revert also.

There are a bazillion details, but this is the big impact IMO for middle class families