Update: I just tried running the game in Firefox and it's working like normal. Try checking your configs and seeing if WebGL is disabled. I found this advice on a unity thread about the same issue. They recommended searching "about:config" then finding "webgl.disabled" and setting it to false.
https://discussions.unity.com/t/uploaded-webgl-not-loading-on-firefox/602279/4
You can also check if WebGL is enabled on your browser by using this website
I hope this helps and thanks for bringing this possible issue to our attention!