Minecraft Dungeons was released before the announcement of the dedicated Minecraft franchise logo. Various materials have the new Dungeons logo with the Minecraft franchise logo, but Minecraft Launcher still uses the Minecraft game logo. 

The Minecraft website is one place that uses the new Dungeons logo that uses the franchise logo. 

https://www.minecraft.net/en-us/about-dungeons

Also affects beta.2.4.2-1.2.4.

This issue is particularly striking as MCL switched to the new logo for the base games (Minecraft: JE and Minecraft: BE) two years before being implemented in Minecraft: JE

This issue also affects Mojira and Minecraft Dungeons itself.