Unable to delete other subscribed calendar on iPhone and iPad in iOS11

For some unknown reason, I have a subscribed calendar listed under <other> in the listing of my calendars in the calendar app. This subscribed calendar can't be deleted nowhere.

I tried clicking on the "i" next to the calednar I want to delete, but there is no option there to delete it.

I tried to go to >Settings >Accounts & Passwords, but there is no account with a subscribed calendar listed there.

I tried to go to the Calendar settings in >Settings, but there is no option to delete calendars there.

When I go to icloud.com this calendar is not listed there. It's also not listed on my Mac, just on my iPhone and iPad.

Any way to have this annoying calendar completey removed from my iPhone and iPad? I understand I can hide the displayed holidays, but I want to remove it entirely!