The problem with this is that when you do it, you're actively looking for lookalike domains. The challenge is when an email or link otherwise seems very legitimate, so you have your guard down.
Anyone else having this issue with the display <a href="https://i.imgur.com/Bk2Gzee.png" rel="nofollow">https://i.imgur.com/Bk2Gzee.png</a><p>Edit: figured it out, it seems the font size is based off of the Window size (which doesn't make any sense) and scales faster than the box scales. Works best if you make your browser window phone width.
I was expecting this to be harder as well. With swapped unicode letters. Maybe you should make them different levels, 1 = easy like you had, 2 = with upside down letters, 3 = greek letter replacement (unicode swapping)
Fortunately I know the form of a URL (anyone who uses them ought to know, and if you don't know, then you must learn), and I use a fixed pitch font on the status bar and location bar. I also fixed it to display only ASCII characters in the location bar, so that homoglyph attacks are also avoided.