What is the issue with the HTML Standard?

The <canvas> DOM element, like all DOM elements, accepts a lang attribute that is used to define location specific treatment for font selection (when fonts have locale specific glyphs). Browsers respect this attribute. However, when an OffscreenCanvas is created in JS, there is no way to set locale information, possibly resulting in a state where an offscreen canvas produces rendered results that differ from the canvas in which it's output is used.

I propose adding an optional string lang parameter to the OffscreenCanvas constructor, and spec text indicating how offscreen canvases created from canvas elements should inherit the lang.

Both Chrome and Firefox on linux always use the system language settings for offscreen canvas, even when transferred from a canvas element, as far as I can tell.