Lately, I've been using https://playnoise.com/ with the following settings: Brown noise > More Options > Auto volume osc, slow, small.

Also, My "Code it and Load it" Playlist on Spotify - https://open.spotify.com/user/bawigga/playlist/08wdT51daeQwc...

Finally, more brown noise/rain storms in my Focus Noise playlist on Spotify - https://open.spotify.com/user/bawigga/playlist/1u2c1lK4YSnL1...