I believe they've all been AUMFs (Authorizations for the Use of Military Force), effectively bypassing various checks and safeguards in place when starting formal wars.
Checks and balances: A formal declaration of war requires a higher level of political support and public debate, providing more opportunity for scrutiny and oversight.
Indefinite conflicts: AUMFs often lack clear objectives or timelines, which can lead to prolonged and open-ended military engagements.
Legal ambiguity: AUMFs can create legal ambiguity, as they may not explicitly invoke the laws of war, which govern the conduct of armed forces and the treatment of civilians, prisoners of war, and non-combatants.