Brave gives a randomized fingerprint when you set the fingerprint blocking to strict. Set the adblocking to strict too, and use adguard for desktop to spoof your user agent to the most common chrome on windows user agent you can find.
I just made a new blank sandbox to visit reddit and they didn't block me
On each page load, Reddit pings home with some of your browser stats, including your user agent. You can't block it (easily) because it randomly uses real API endpoints for the ping, for example it will ping to /api/comment which is used to post comments so if you block that you can't post...
What I'm getting at is, they must be collecting that data for something, and doing it this way is obviously an attempt to fingerprint.
Oh and if you're using multiple accounts in the same browser without containers/incognito/profiles then they know about it, they keep data on the browser about all of them and send it to the server so it can correlate them.