Embedding Code does not work with small height

Steps to reproduce

1. Get a new account from https://try.nextcloud.com/ / or selfhosted
2. Add an event to your personal calendar (important, without events it works)
3. Share your personal calendar and copy the embedding code
4. Paste Code into HTML Document or on jsfiddle.com etc.
5. Open File in browser (may not work in Chrome? / jsfiddle

Expected behaviour

We should be able to change views, change months etc.

Actual behaviour

Nothing happens. Well you see a change in UI Elements, but the calendar view does not change.

When setting the height of the iframe to something like 450px it works, but only if you added only one or two event on different days. If you add more events (like 4-6) it breaks again until you increase the height of the iframe.

Calendar app

Calendar app version: 2.1.3

Client configuration

Browser: Firefox 85 / Chrome 88

Operating system: Ubuntu / Arch Linux

Server configuration

Operating system: Debian
Web server: Nginx
Database: MariaDB
PHP version: 7.4

Nextcloud Version: 20.08

(or see try.nextcloud.com)

Start by reproducing the embedded personal calendar with a small iframe height, first with one or two events and then with four to six, using the provided browsers or jsfiddle.com. Done means changing views and months works reliably regardless of the number of events or iframe height.