reCaptchaV3 not working on mobile

Hi,
I’ve got a quite standard form on my site, https://waternatuurlijkdodelta.nl/contact-over-de-verkiezingen/ with a redirect to a thank-you page, a confirmation email to sender and to the webmaster.

Problem is: it works fine when filling in on a computer or laptop (although the email to sender is delivered in the spambox, but that might be an issue with my emailprovider), but on mobile (I tried iPhone and iPad), the form gives an orange warning ‘message not sent, try again’. There is no redirect or sending message to sender or webmaster. Nevertheless, the information from the mobile entry (so the form that seemed not to be sent) is stored in the spambox (I use Flamingo), so somehow there is communication.

I disabled Recaptcha V3, after that the form on my iPhone worked. I found a solution by installing the plugin ReCaptcha v2 for Contact Form 7, but I would rather have V3 working. Is there a solution for this issue?

The page I need help with: [log in to see the link]