I work for a City Government as a GIS Analyst.
In our efforts to address ADA accessibility issues, we have found that the text card built in features often result in accessibility issues because of poor design. Specifically, the style button presents headers as if they are selection of font sizes, resulting in header structures being used incorrectly. This disrupts screen readers and tab navigation for people with disabilities. Additionally, when the header is clicked on but nothing is inserted, this creates an empty header, which is a WCAG standard violation. Users that do not edit the html directly may not know that an empty header was created and may publish a page without knowing that there are accessibility issues. We have consistently found these issues as the most prevalent issues across all of our hub sites.
Potential solutions could include adding a font size button to avoid confusion with the heading structure, and to specify heading structure best practices in the text card (with a link or a help button). The text card could also suppress empty headings.