Browser isn't supported by MRBS

Description

I am running Brave v1.73.104 and NixOS 25.05. The dotfiles for my system can be found here: https://github.com/Gooxey/dotfiles (The error will happen on both the kraken and squid config)

On interactions with the website https://merry.ulb.uni-bonn.de/mrbs_ulb/web/index.php I get the error Unfortunately your browser isn't supported by MRBS. You will need to upgrade to a more recent version, or else use another browser.

Steps to reproduce

1. Run NixOS with the config found here https://github.com/Gooxey/dotfiles (kraken or squid profile)
2. Open Brave and go the website https://merry.ulb.uni-bonn.de/mrbs_ulb/web/index.php
3. Click on any day of the Calender on the right or on the Today button at the top or on any of its next/prev buttons.

Actual result

On interaction with the aforementioned website, pure HTML without any CSS got rendered with the error (under the first picture and link) Unfortunately your browser isn't supported by MRBS. You will need to upgrade to a more recent version, or else use another browser.

Expected result

The page should display as normal. I had the expected results when using Firefox.

Reproduces how often

Easily reproduced

Brave version (brave://version info)

Brave: 1.73.104 Chromium: 131.0.6778.204 (Official Build) (64-bit) Revision: 215b794a7c1f3e28151d0f7712e32c71be48775c OS: Linux

Channel information

• release (stable)
• beta
• nightly

Reproducibility

• with Brave Shields disabled
• with Brave Rewards disabled
• in the latest version of Chrome

Miscellaneous information

No response