We noticed a couple of Adyen Apple Pay failmails which suggested there was a timeout at Ayden's end. However, when looking at the logs, it looks like we did get IPNs sent over for these payments and the IPNs came back with the following:

<eventCode>AUTHORISATION</eventCode>
<eventDate>2021-11-30T20:47:35+01:00</eventDate>
<merchantAccountCode>WikimediaDonations</merchantAccountCode>
<reason>Issuer Unavailable</reason>
<success>false</success>

sample ct_ids:
109355041
109212219

Looks like we only got eight of these but could possibly pick up as yesterday was our first busy traffic day offering Apple Pay. The fact that they coincided with a timeout makes me wonder if Adyen's internal calls are timing out when we make a certain type of request. One to monitor!