This has been bothering me for a while and I just searched the forum and couldn’t find any bug reports about it.
If you assign a class to icons in Bricks and style them on the class, the styling on the frontend is still based on the ID. https://mellow-wave-74314.wp1.site/icons/
The problem is, that SVG controls are not the same type of controls as other ones, so that’s why there is this difference. We know it, and we have an internal task for it. But for now, there is no easy fix for this, unless you don’t use those controls and you style just element with “normal” controls or add custom CSS.
I’ll link this thread to the task so that it will updated once we have a fix/improvement for this, and I’ll mark this thread as DUPLICATE and close it.