I believe that’s possible if you don’t wait for the font. Depending on how early in the script your ADT is created. Eventually, this could also occur now and then in some other browsers depending on the speed at which the host delivers the different parts. If you don’t want this to happen, I think awaiting the font for the ADT would be the better solution for consistency. Depending on your scene and how many things you are loading async, the loading of a single fontface should not impact the loading time (unless it’s stuck somehow). Of course, my opinion only.
Sure, I understand. And now I have this.
But then we cannot say, that just having link in html and font-face block in css are enough.
No. You got this right. This is why older users and game creators in this forum came-up with this piece of code you found that ensures the font is loaded in the canvas. I understand it’s not the most ‘sexy’ for an eng, but - since I’m no eng - I tend to put ‘consistency’ above ‘performance’ or code optimization so to say… up to a certain point, of course 
I guess it’s all a thing of finding a balance between pros and cons… until we eventually get a better solution 
I did test on Firefox too and I couldn’t see the font changing, it was always being loaded correctly. But browser behavior is not always consistent, so I agree with mawa that explicitly using FontFace is the best option to avoid any problems.