Login takes forever

### Steps to reproduce

Since around two weeks ago, trying to log into our self hosted server just loads forever. Previously this worked fine.


I then need to click on "Logout" and enter my credentials and recovery key to login. The next time I close and open the tab, this happens again.

It seems that in the background some requests take a long time:


I'm on Firefox 128.9.0esr, but other users have reported the same issue with Safari and Chrome.

The server is hosted and updated by etke, but I can provide logs and data as needed.
Currently the latest version v1.11.99 is running.

I appreciate any help!

### Outcome

#### What did you expect?

The login to succeed.

#### What happened instead?

The login takes forever.

### Operating system

Debian Linux

### Browser information

Firefox 128.9.0esr but also in other browsers as noted above

### URL for webapp

https://element.fossi-chat.org/

### Application version

v1.11.99

### Homeserver

Synapse v1.128.0

### Will you send logs?

Yes