Dalaran Heist: Doppelgangster does not apply "permanent" friendly encounter buffs to copies

https://www.reddit.com/r/hearthstone/comments/bpoxcy/bartenders_give_a_minion_44_it_costs_2_more_does/

In a similar but less widely reported case, Spellstones don't seem to retain these discounts when they upgrade, even though they do retain normal cost modifiers (#874): https://us.forums.blizzard.com/en/hearthstone/t/0-mana-spellstone-becomes-7-mana-after-upgrading/5815

I got a 0 mana spellstone in the Dalaran Heist ,during the tavern, and when it upgrades, it loses it’s 0 mana value

To make sure this was a bug I made a deck with far sights and lesser sapphire spellstones and played against the innkeeper. I managed to pull a lesser sapphire spellstone from one of my far sights making it cost 4, and upgraded it all the way to greater sapphire spellstone and its cost remained 4, which makes me think that the bartender bonuses not remaining with the upgrades is indeed a bug.

It seems the buff considers itself created by the minion that it's attached to:

SHOW_ENTITY - Updating Entity=[entityName=UNKNOWN ENTITY [cardType=INVALID] id=78 zone=PLAY zonePos=0 cardId= player=1] CardID=DALA_908e
    tag=CONTROLLER value=1
    tag=CARDTYPE value=ENCHANTMENT
    tag=ATTACHED value=24 <-- (Entity ID of an Arcane Anomaly)
    tag=DAMAGE value=0
    tag=ZONE value=PLAY
    tag=ENTITY_ID value=78
    tag=ZONE_POSITION value=0
    tag=NUM_TURNS_IN_PLAY value=0
    tag=CREATOR value=24 <-- (Same Arcane Anomaly it's attached to)
    tag=CANT_BE_SILENCED value=1
    tag=TAG_LAST_KNOWN_COST_IN_HAND value=0
    tag=479 value=0
    tag=1037 value=0
    tag=1068 value=0
    tag=HIDE_WATERMARK value=1
    tag=1254 value=0
    tag=CREATOR_DBID value=39215 <-- (Card DBID of Arcane Anomaly)
    tag=UI_BUFF_HEALTH_UP value=2
    tag=UI_BUFF_ATK_UP value=2

It's possible there's some check to ensure that the buff cannot be attached to a different card ID.

HearthSim / hs-bugs

Dalaran Heist: Doppelgangster does not apply "permanent" friendly encounter buffs to copies #1187