If you move around a Pillager (in Survival or Creative), as long as they are not doing the animation to charge their crossbow, their left arm will not turn with the rest of their body properly.
(Video taken in 19w40a, screenshot from release 1.14.4)
Thank you for your report!
We're actually already tracking this issue in MC-139528, so I resolved and linked this ticket as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature in the future to see if the issue has already been reported.
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