Ok after some looking I’ve discovered this out:
Yellow objects are bonus objects given in your first Pokestop of the day.
Yellow objects are additionally given at Gyms you probably have a Gym badge
Blue/Red/Presumably yellow for Instinct? objects are given at Gyms while you spin a disc on a Gym that your staff
In your instance the Pokestop will need to have been your first of the day, therefore yellow objects. The different two are gyms managed by your staff, each of which you’ve a fitness center badge for, so you bought yellow and blue objects.
This man appears to verify this.
Niantic affirm the Gym facet.