The Bug:

Players' arms follow the position of sneaking players when preparing to throw tridents.

Judging by the assigned Mojang Priority on MC-190817, players' arms should not follow the position of sneaking players when holding loaded crossbows or fully charged bows. With this in mind, one would expect players' arms to not follow the position of sneaking players when preparing to throw tridents.

Steps to Reproduce:

1. Obtain a trident, hold it, and prepare to throw it.
2. Switch to third person and begin sneaking, and as you do this, look at the position of the arm that's used to hold the trident.
3. Take note as to whether or not players' arms follow the position of sneaking players when preparing to throw tridents.

Observed Behavior:

Players' arms follow the position of sneaking players.

Expected Behavior:

Players' arms would not follow the position of sneaking players.

Code Analysis:

Code analysis by Apollo30 can be found in this comment.