The bug
Only a few amount of illusioners hold their bows more diagonally. https://minecraft.gamepedia.com/Illusioner
How to reproduce
Summon a lot of illusioners.
Summon a NoAI villager.
If lucky, one of the illusioners will hold their bows diagonally while others hold it like skeletons.
Related issues
Attachments
Comments

Thank you for your report!
We're actually already tracking this issue in MC-48071, so I resolved and linked this ticket as a duplicate.
However, that ticket has already been resolved. That means that this is not considered a bug and won't be fixed. Please do not leave a comment on the linked ticket.
If you haven't already, you might like to make use of the [search feature|https://bugs.mojang.com/issues/
] in the future to see if the issue has already been reported.
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Fixed in 1.15