Choosing to focus on healthcare subsidies instead of Congressional Republicans' lack of oversight of the President while most of the government is shut down by fiat and the President deputizes fundamentalist militias to attack and ransack blue states and cities was its own sort of own-goal as well. Turmp has shown that people want politicians that will stand up for something, even if that something is utterly horrible and self-destructive policy. Democrats must wake up to their pressing need for some spine transplants, ideally sooner rather than later.
The average American voter has the attention span of a goldfish. (Or at least, those who matter do; everyone else has already made up their mind and won't switch.) You won't get them by talking about constitutional limits of the executive branch, Trump ignoring congressional oversight, and such. Remember that there are people who googled "did biden drop out" on Nov 5, 2024.