Looking into Tasha’s Cauldron of Everything, I was reviewing the stat block of the Fey summoned by the Summon Fey spell. Amongst the statistics provided is the Proficiency Bonus of the spirit, defined as "equals [the caster’s] bonus."
The Summoned Fey has no Skill, Tool, or Saving Throw Proficiencies. Presumably the Proficiency Bonus value is already effectively baked into the Shortsword Attack, and the Spell Save DC for its bonus actions, as those are based on the Caster’s Spell Attack and Spell Save DC.
Is there another reason why the Player or DM would need to know this Proficiency Bonus, or is it merely a leftover from using a similar Stat Block for companions that do have proficiencies, such as the Battle Smith’s Steel Defender, or the Homunculus Servant Infusion?