I just opened it again to make sure I wasn't imaginging it. Oddly enough, A works to strafe left for me, but D doesn't work to strafe right. I'm using Firefox 121.0.
If someone is using Vimium or something similar and aren't aware yet, entering input mode, usually 'i', will let key-presses slip by the plugin input parser and go straight to the web page.
Edit: ignore me! It's one of my plugins!