Steps to reproduce the issue

Use the following IcoMoon icons:
class="large-icon icon-expand-2"
class="large-icon icon-contract-2"

Expected result

Display as documented here:
https://docs.joomla.org/J3.x:Joomla_Standard_Icomoon_Fonts

There appears to be no equivalent J4 page.
Still expect the same result.

Actual result

As screenshot1.png
Extract of the HTML is screenshot2.png

icon-basket is showing instead of icon-contract-2

System information (as much as possible)

Windows 10 client and Apache server.
PHP 8.0.3
Browser : firefox & chrome
Joomla template : cassiiopeia

Additional comments

Same code was ok on J3.