Banking wont allow SAFARI to download/view PDF statement

For a number of updates (maybe 4 years) I've checked if SAFARI has changed to enable me to use the NatWest banking app on-line. I can't download/view PDF link to statements/transactions. When the linked file is clicked, the download list flashes and shows unknown file (stopped) and the icon wont even "appear" in the list if it was previously cleared.

SAFARI works as advertised on other pages, animating the file to the download list, or with shortcut keys view etc.,

I've tried;

1) open safe files when downloading (off/on - SAFARI settings)

2) spoofing the website using developer using "Chrome for MAC"

3) banking website works with Brave/Firefox and Chrome (all used on my MAC for faultfinding)

PDF file is underlined (linked) but seems to force download if clicked. That is not normal as SAFARI would "normally" display and I'd have to use a shortcut key to open in another tab or download.

The link will work when accessed in iOS SAFARI and then I share the displayed outcome via AirDrop to MAC - so iOS SAFARI works as it should.

How do I fix this or report it as I can only demonstrate the problem using a secure and private banking web hosted page?

MacBook Air Retina, 13-inch, 2020

Sonoma 14.4.1 (23E224)

SAFARI 17.4.1 (19618.1.15.11.14)

iOS 17.4.1