Strange content encoding selected by compression middleware

I'm using Traefik 3.1.2 with compression enabled (default settings). When specifying the weight/quality value I'm seeing some strange behavior. Could someone maybe explain the logic behind these results?

Accept-Encoding Content-Encoding
gzip, br br (correct)
br, gzip br (correct)
gzip;q=0.9, br;q=0.9 gzip (wrong)
gzip;q=0.9, br gzip (wrong)
br;q=0.1; gzip br (wrong)

Reference to quality values.