Earlier quoted context omitted.
No need to wonder. You can read the poll and results methodology yourself. The answer is two clicks from the article, both links above the fold on their respective page. If you’re being genuine in your curiosity, it would improve the discussion here if you shared what answer you find.
> The survey was designed to reach adults who currently have health care debt or have had health care debt in the last five years . In order to do this, the probability panel sample included an oversample of panel members with annual household incomes less than $30,000, individuals with current or past health care debt (n=641) were included in the sample. In addition, 52 adults with past or current health care debt w…
No, that's not how it works. You oversample a group you are interested in and then weight it.
To be honest, you don't know enough about statistics to evaluate this. You should either learn more or accept the conclusions of those who know more.