There are numerous reasons not to use icon fonts in place of images, but the main ones relate to accessibility:

-They confuse screen readers. Often read in strange ways or simply as 'unpronouncable'
-They don't include metadata or image alt text for screen readers
-They don't play nice with style-sheet changer like dyslexic font plugins (see below)

Here is a more detailed article on the issue by Michael Irigoyen:
https://www.irigoyen.dev/blog/2021/02/17/stop-using-icon-fonts/