Oh, you did say it occured in every game you uploaded. While you are at it, I think you did something with the mouse cursor, that should not be done. It is showing the cursor but you use mouse as input for turning. And on screen edge, the cursor stops and you cannot turn further.
https://docs.unity3d.com/Manual/webgl-canvas-size.html
I still do not know any unity, but from that read it sounds like you decoupled the the render, but should not have done so, since you do want the automatic scaling.