I have the same problem using music.amazon.de described at "Amazon Music" complaining about old version of Chrome.
I’m using the latest version of brave:
0.66.101 Chromium: 75.0.3770.142 (Official Build) (64-bit)
Widevine Content Decryption Module - Version: 4.10.1440.18
Shields are down, permissions are granted.
Is this a known problem?