Note
This is not a report about how blocks held by endermen do not emit light. Please consider that. (Thanks!)
The bug
When endermen are summoned holding fire, soul fire, campfires, or soul campfires, the fire is rendered too dark. This can easily be reproduced by running the command:
/summon minecraft:enderman ~ ~ ~ {NoAI:1,carriedBlockState:{Name:"fire"}}
and then lighting a fire next to the enderman.
[media]Observed Behavior
Fire and campfires held by endermen are rendered too dark.
Expected Behavior
Fire and campfires held by endermen would not be rendered too dark. They should be rendered the same brightness as how these blocks appear when placed down.
Can confirm in 21w03a.