Hassio 74.2 - only just noticed it but may have happened sometime ago…
I have for instance the following in customize.yaml
switch.lava_lamp:
friendly_name: 'Blue Lava Lamp'
entity_picture: /local/lavalamp.jpg
assumed_state: false
switch.epson_proj_poweron:
icon: mdi:projector
These used to work but now they all just show the lightning bolt and not the mdi or icon the docs state that we can still use them, so I think they should still work?