Spotify doesn’t make changes like that on its own, the artist probably did that for a reason

My guess is stylistic choice by the musician to make it clear the first letter is an “i”

Either a typo or stylistic choice.

MusicBrainz has it capitalized https://musicbrainz.org/recording/a6c4fbb5-f8ef-4d40-823a-1a47ae671ca4

ileso

Ileso

Which is easier to read? Ileso could be confused for lleso I guess. Typesetter did their job right here.

What music player is this? :)