Hi, WebGL unity dev here. Would you mind checking if "Decompression Fallback" is on? Check out the manual if lost ♥
Also keep in mind that site cache might mess with WebGL so better wipe it each new version)
Site caching is a browser feature. Found a link to describe, how to do it, and only for a specific site.
And a little note from myself, I did notice that "jump" sound is played whenever button pressed, but if I spam it mid-jump, trying to get over croud in spa, it might be a little annoying. So a simple condition check "play sound if character grounded" would be great (or "play sound if char vertical speed is zero,", pick whatever suits you)