List Layout only shows top 20 messages if there's no vertical scrollbar (tall screen, tiny text)

Steps to reproduce

1. Have more than 20 messages in your E-mail Inbox
2. Open your Inbox -- for me it's https://cloud.SOMEDOMAIN.de/index.php/apps/mail/box/MYnumericalID#
3. In the Mail settings, set "Layout" to "list" (hope that's the name, I'm translating from German "Liste")
4. Make sure you see the list of messages in your Inbox, and make sure your window height can show more than 20 liste rows at a time (!!). (I'm using my 1920x1200 px screen in "portrait" orientation. You could even zoom out...)
5. If needed, reload the page to see that...
6. ...only the first 20 messages are shown (as list rows) in your Inbox! (That's the actual bug.)
7. Since there's no scroll bar (Window is taller than required to show those 20 list rows), there's no obvious way to load more messages, or even just to tell that there are more messages in that folder (Inbox).
8. Reduce the Window height (or zoom in) to make the vertical scroll bar appear
9. Scroll down -- additional messages (beyond the top 20) appear.

Expected behavior

If possible (enough messages in the folder), the message list should always show so many rows that a vertical scrollbar is shown and I can use the "infinite scroll" to load more messages.

Actual behavior

If the first 20 messages fit into the Window without a scroll bar, I'm not given any hint to tell that the folder contains more messages, nor is there a way (e.g. by scrolling) to display and open them.

Mail app version

5.11.5

Nextcloud version

33.0.3.2

Mailserver or service

No response

Operating system

No response

PHP engine version

None

Nextcloud memory caching

No response

Web server

None

Database

None

Additional info

I'm not an admin of this Nextcloud instance, therefore cannot provide the technical details I've left blank.

Start by reproducing the issue in the Mail app's list layout with more than 20 messages and a window tall enough to avoid a scrollbar. Trace the list-loading or infinite-scroll entry point and compare behavior when the viewport is shorter. Done means additional messages can be reached or a scrollbar is available without resizing or zooming the window.