Open Netflix again. You should be streaming in 1080p (or 4K, depending on your plan) immediately. While the fix above gets you streaming, you should know the limits. Due to licensing restrictions from Google and Netflix, Brave (like Firefox) is generally limited to 720p or 1080p.
Most browsers (Chrome, Edge, Opera) ship with this key pre-installed. Brave is built on Chromium (the same engine as Google Chrome). However, Brave removes many Google "phone-home" features to protect your privacy. google widevine brave
If streaming breaks again after a Brave update, simply revisit brave://components and click "Check for update." It takes three seconds. Do you use Brave as your daily driver for streaming? Let us know in the comments if you hit the 1080p limit or if it works perfectly for you. Open Netflix again
Here is the issue: It is not open source. Due to licensing restrictions from Google and Netflix,
Once you manually enable Widevine via the components page, Brave behaves identically to Chrome for streaming, but with ad-blocking and tracker protection turned on.