Subscribed Calendar - ICAL file shows 1230 finish, shows on phone and ipad as 1330 finish.

Hello

I subscribe to a calendar for work.

The start times are all correct. The finish times, however, are not.

It is not a time zone issue.

Apple seems to be adding time to the length of the appointment - the ICAL file itself is also correct when downloaded and viewed in a text editor.

The ical file says:

DTSTART;TZID=Europe/London:20210412T103000

DTEND:20210412T123000

Any ideas?

This is happening on iPhone, and 2 iPads.