MC-268147 Breaking shield triggers invulnerability tick behavior, despite player not turning red - Jira (mojang.com)
This issue exists in versions prior to 1.20.6 however most players would not know this because paper servers up until 1.20.5 did not trigger i-frames upon shield disable
MC-268147 Breaking shield triggers invulnerability tick behavior, despite player not turning red - Jira (mojang.com)