**Summary:** * Unchecked Drupal checkboxes serialize as `"0"`. * `transforms.cast` only treats `'false'` as false, then `Boolean(value)`. * `Boolean("0") === true` → unchecked booleans flip to `true` on auto-save when another field changes. **Repro:** 1. Component with two boolean props (e.g. Hero Standard `popup_form` + `ppc_header`). 2. Open in Canvas editor; leave `popup_form` unchecked, toggle `ppc_header`. 3. Observe `popup_form` saved as `true`. **Fix:** Explicit handling when `to === 'boolean'` for `'0'`, `0`, `''`, `null`, `'false'`.