Summary:

Known issues with chunk generation order affecting world generation cause stronghold chests to generate different loot on the same seed.

Steps to Reproduce:
1) Load the seed 157

2) /tp 1380 28 803

3) Note the contents of the lower library chest.

4) Recreate the seed and teleport to a different position, loading the chunks in a different order. For example: /tp 1411 24 791

5) Travel back to the lower library chest at 1380 28 803, the contents will vary.

Expected Behavior:
Each world seed should generate with the same chest loot

Observed Behavior:
Each instance of certain seeds can generate different chest loot

World Seed: 157

Additional Information
This issue seems to exclusively affect stronghold chests in a chunk where a cave intersects the stronghold, varying the number of stone bricks caused by cave differences from different chunk generation order. See MC-55596 and MC-219200  for more examples of this behaviour.

As the stronghold chests use the same random number generator as the stronghold stone brick randomization uses (when choosing mossy, cracked, or regular variants), and this randomization is not performed if the block is replaced by a cave's air, the contents of the chest will vary depending on the order in which the chunks were generated.

Chests should either perform randomization independent of stronghold stone brick variants, or cave variation should not cause stone bricks to stop their randomization attempt.