The 2024 PHB says the Circle of the Stars Druid can have Guiding Bolt prepared if they use their Star Map as a Spellcasting Focus. A tag could be added to this page for that subclass unless that's too "situational". A different example would be the Pact of the Tome Eldritch Invocation which allows Warlocks to prepare two of any class's level one ritual spells and those spells don't have the Warlock tag on them. 

Quote from DthEtr >>

The 2024 PHB says the Circle of the Stars Druid can have Guiding Bolt prepared if they use their Star Map as a Spellcasting Focus. A tag could be added to this page for that subclass unless that's too "situational". A different example would be the Pact of the Tome Eldritch Invocation which allows Warlocks to prepare two of any class's level one ritual spells and those spells don't have the Warlock tag on them. 

Pact of the Tome also allows getting several cantrips from any class list, so by that logic every cantrip should have the Warlock tag on it because a Warlock could potentially get it. And almost every level 1 spell should have every class's tag on it because anyone could take the Magic Initiate feat and get them that way. You gotta draw the line somewhere.

Maybe this is a bit pedantic, or more based on a video game understanding of buffs and debuffs, but this does feel like a debuff. This is an effect that makes it harder for an enemy to fight, as it is tied to the enemy being hit and not the ally making the attack.

You could have just said that it's too situational.

Nerf this spell.