Based on the description it solves exactly your issue, but requires iOS 26/macOS 26.
Personally I use Adguard + their DNS. This combination is very good, but WebView blocking will be working with the DNS part, not content blocker. So alternative is PiHole.
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You can try Wipr2/Filtr: https://kaylees.site/wipr2-whats-new.html
Based on the description it solves exactly your issue, but requires iOS 26/macOS 26.
Personally I use Adguard + their DNS. This combination is very good, but WebView blocking will be working with the DNS part, not content blocker. So alternative is PiHole.