How does the WhatsApp web client still work with the latest iOS update (SDK version 13.0+)?

This is WhatsApp latest entitlements file:

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"><plist version="1.0"><dict>    <key>com.apple.developer.icloud-container-identifiers</key>    <array>        <string>57T9237FN3.net.whatsapp.WhatsApp</string>    </array>    <key>com.apple.developer.pushkit.unrestricted-voip</key>    <true/>    <key>com.apple.developer.ubiquity-container-identifiers</key>    <array>        <string>57T9237FN3.net.whatsapp.WhatsApp</string>    </array>    <key>application-identifier</key>    <string>UKFA9XBX6K.net.whatsapp.WhatsApp</string>    <key>com.apple.developer.carplay-messaging</key>    <true/>    <key>aps-environment</key>    <string>production</string>    <key>com.apple.developer.icloud-container-environment</key>    <string>Production</string>    <key>com.apple.developer.associated-domains</key>    <array>        <string>applinks:api.whatsapp.com</string>        <string>applinks:v.whatsapp.com</string>        <string>applinks:chat.whatsapp.com</string>        <string>applinks:wa.me</string>    </array>    <key>com.apple.developer.siri</key>    <true/>    <key>com.apple.developer.team-identifier</key>    <string>57T9237FN3</string>    <key>com.apple.developer.icloud-services</key>    <array>        <string>CloudDocuments</string>        <string>CloudKit</string>    </array>    <key>com.apple.security.application-groups</key>    <array>        <string>group.net.whatsapp.WhatsApp.shared</string>        <string>group.com.facebook.family</string>        <string>group.net.whatsapp.WhatsApp.private</string>        <string>group.net.whatsapp.WhatsAppSMB.shared</string>        <string>group.net.whatsapp.family</string>    </array></dict></plist>

This specific entitlement seems to be the reason that they are allowed to not report an incoming call:

com.apple.developer.pushkit.unrestricted-voip

I can't find any documentation regarding this entitlement, so I'm pretty sure they have been given a special permission by Apple.

I've asked eurodev support about this and just received:

At this point we don’t have any additional information about the unrestricted entitlement that you are asking about. The only information that’s available is linked here.

https://developer.apple.com/documentation/bundleresources/entitlements

Pushing back to them to get more info.

Thanks.