Here are some external sources that support to notion of "regressive" as meaning "having a backwards or detrimental effect on progress and equality." The term "regressive" is often used in the context of taxation policy but is also applicable to gender equality and other social issues as well.
Working Paper from Boston University Global Development and Environment Institute, "Progressive and Regressive Taxation in the United States: Who’s Really Paying (and Not Paying) their Fair Share?"
A regressive tax system is one where the proportion of income paid in
taxes tends to decrease as one’s income increases.
Article on Climate Change and Global Inequality from the United Nations Development Programme
And while fossil fuel subsidies are regressive – and therefore
constitute an unequalizing tool, they also represent a significant
share of the incomes of the poor that otherwise would be paid for
Article from the World Bank, "Is Tobacco Taxation Regressive? Evidence on Public Health, Domestic Resource Mobilization, and Equity Improvements" (includes links to PDF and text versions of the article)
Another often-cited concern among policy makers is that tobacco taxes
are regressive, as they disproportionately burden poorer smokers, who
spend a larger portion of their incomes on tobacco products, relative
to wealthier consumers.
Entry from World Bank Blogs, "Helping families cope with price shocks—without subsidies"
However, subsidies are undesirable for a number of reasons. First and
foremost, they are regressive—that is, they benefit richer families
more than poorer families, and they are highly expensive.
Article from the World Bank Open Knowledge Repository, "Measuring Equity in Health Care Financing : Reflections on (and Alternatives to) the World Health Organization's Fairness of Financing Index"
[P]olicymakers who may be strongly averse to regressive payments
(which worsen income distribution) may in the name of fairness be
quite receptive to progressive payments (requiring that the
better-off, who may be willing to spend proportionately more on
health care, are required to pay proportionately more).
Article from the Center for American Progress, "Authoritarian Regimes Have More Progressive Abortion Policies Than Some U.S. States"
Americans in states with regressive anti-abortion laws now have fewer
human rights protections than those in countries criticized for their
records on women’s rights.
Article from Morgan Samuels Company, "Addressing the Regressive Impacts of the Pandemic on Gender Equality"
[I]t has become apparent that the COVID-19 pandemic is having a
regressive effect on gender equality. Decades of improvement may be
lost, as progress stalls and women find their place in the work force
more at risk. In early 2020, the World Economic Forum predicted it
would take 100 years to close the global gender gap, but it is
expected to take even longer now with the setbacks from the pandemic.