A contract doesn't protect your data from government searchs, with or without warrant.
1. A ZDR clause is "trust me bro". You have zero way of verifying their pinky-promise.
2. A ZDR clause is still subject to the old-classic "government, court or administrative order" catch-all clause. :)
3. "Even with ZDR enabled, Anthropic may retain data where required by law or to address Usage Policy violations. If a session is flagged for a policy violation, Anthropic may retain the associated inputs and outputs for up to 2 years, consistent with Anthropic’s standard ZDR policy." (I quoted Anthropic, I'm sure all the others have similar).