@glyph It is Spotlight. Apple documents that now to head off people who insist they’re ruining batteries for “planned obsolescence”.
@glyph “Immediately after completing an update, particularly a major release, you might notice a temporary impact on battery life and thermal performance. This is normal, as your device needs time to complete the setup process in the background, including indexing data and files for search, downloading new assets, and updating apps.”
If you have a fediverse account, you can quote this note from your own instance. Search https://infosec.exchange/users/ubernostrum/statuses/115220985700307223 on your instance and quote it. (Note that quoting is not supported in Mastodon.)