Greylist delay no good with info that expires quickly

I’ve had a frustrating afternoon. My bank sent a link by email that expired after 15 minutes.
But greylisting delayed the email. Why does miab greylist such an email, and can you change the delay?

X-Spam-Score: -4.2
X-Greylist: delayed 900 seconds by postgrey-1.36 xxxxxxxx.co.uk; Thu, 17 Oct 2024 15:17:20 BST
Authentication-Results: xxxxxxxxx.co.uk; dmarc=pass (p=reject dis=none) header.from=communications.santander.co.uk
Authentication-Results: xxxxxxxx.co.uk; spf=pass smtp.mailfrom=bounce-JGAMZEMUZCXUVMXDJ2XFSQ4L5I.510004@bounce.communications.santander.co.uk
Authentication-Results: xxxxxxxx.co.uk

Please use whitelisting. This is the only solution for now.
Read here: How to use Postgrey client whitelists