If the taxpayer is paying for the grant, I have zero problems with them paying for publishing of the research.
If you summarize the cash flow, the publishing industry charges twice the taxpayers in addition to the science worker and research institutions costs. If you want to make your article open access, then you pay extra fees and nowadays, the university funds ripped off twice: they still bear the cost of pay-wall publishers and open access. Long story short, the whole system is rigged in favor of gatekeepers. You may check this video[1]
Net effect could swing either way.