That didn't either, but I hope this goes to show that dndbeyond links aren't necessarily RAW. As I said, the servant's PB is explicitly listed in the book as +7, not +2.
I think that's a more garden-variety typo. The version that is written out in the Tasha's sourcebook (see https://www.dndbeyond.com/sources/tcoe/magic-items#MagicItemsMP ) shows "Challenge -" and "Proficiency Bonus +7" as appropriate. But the creature statblock that dndbeyond created swapped that to "Challenge 0" and "Proficiency Bonus +2", probably through automated formula after reading "-" as "0" and applying the table in the MM introduction. And the magic item standalone page doesn't show either, but links to the (typo'd) creature entry rather than the one embedded in the Tasha's magic items section.
I think that's a more garden-variety typo. The version that is written out in the Tasha's sourcebook (see https://www.dndbeyond.com/sources/tcoe/magic-items#MagicItemsMP ) shows "Challenge -" and "Proficiency Bonus +7" as appropriate. But the creature statblock that dndbeyond created swapped that to "Challenge 0" and "Proficiency Bonus +2", probably through automated formula after reading "-" as "0" and applying the table in the MM introduction. And the magic item standalone page doesn't show either, but links to the (typo'd) creature entry rather than the one embedded in the Tasha's magic items section.
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I'm going to make this way harder than it needs to be.