Firefox on Windows has scaling problems for ultrawide aspect ratios

On Windows I have weird scaling problems running ABRP in Firefox on my 3440×1440 Monitor. As soon as the Window gets wider than ~2050px the map container does not seem to grow further, while it works fine at smaller widths. The map content get’s squished instead, containing all the content that should be visible for that window size, but instead of stretching the full Window, a white bar appears at the righthand side.

This problem has been there for a while before 7.0.0 and seems to only affect Firefox on Windows. Firefox on Linux and Edge on Windows behave as expected. I haven’t gotten around to testing on a different System or Firefox installation yet.

Screenshot

Recording of it changing