Hey Sebastian,
thanks for your report.
Before Bricks 1.8.4 an SVG within the logo element was output inline. That’s why it was working to target specific parts of the SVG using CSS.
However, with this approach things like the “logo inverse” setting did not work as expected (see related forum report).
So if you want to use an SVG as your logo and you need to style it using CSS please use a regular div (for the link) and an SVG element from now on. This approach does not have any downsides – actually you are even more flexible. 
Best,
André