Minecraft store not loading when trying to give consent to kid’s account

https://checkout.minecraft.net/en-us/store/validate-consent looks like an empty page — I only see Minecraft header and footer, but the middle 80% is all white.  I briefly see a green activity indicator like it’s loading, but it quickly disappears.

I am trying to set up java edition for my kid. Using their account I requested parental consent. I got the consent request email in my account as expected, but clicking the links to give consent and redeem a code leads to the page with an empty body.

This is on Safari 11.1.2 on macOS (admittedly an old version) and also the current version of Safari on iOS. And Firefox 78.9.2esr.

Thanks,
Alex