Summary
Explosions caused by "explosion" mechanic starts from the caster, not from the location where it explodes. Since it's hard to describe, the below video helps illustrate the bug. https://youtu.be/Q6D84s29ACA Steps to reproduce
Server version: Paper 1.21.11 MythicMobs: 5.11.2-SNAPSHOT MythicCrucible: 2.4.0-SNAPSHOT (the same snapshot that attempts to fix #2137)
Current behavior
The explosion damage is based on where the explosion takes place (where the particle is shown), however, whether the damage is blocked by shield is determined by the caster location
Intended correct behavior
More consistent behavior: The explosion damage is based on where the explosion takes place (where the particle is shown). And to block the damage caused by the explosion, you need to move camera to the explosion source (the particle), not the caster.
Additional Suggestion:
There would be an option to set whether explosion can damage the caster