Exactly this. The Moto G6 boot animation resembles more a video game cut scene. Its inappropriately loud and flashy and doesn't match the rest of the Moto G5/G6 experience. It cannot be muted, I hated rebooting it.

Edit: it can be switched off. settings=> sound=> advanced=> startup sound

https://m.youtube.com/results?search_query=hello+moto+boot