ComponentLookupError for JSONField in tests

Tests for a change in are fine (tox).

But CI tests raise a ComponentLookupError for an ordinary plone.schema.JSONField.
Any hint is welcome.

      File "/home/runner/work/", line 45, in update
      File "/home/runner/work/", line 62, in update
      File "/home/runner/work/", line 31, in GroupForm_update
      File "/home/runner/work/", line 132, in update
      File "/home/runner/work/", line 136, in updateWidgets
      File "/home/runner/work/", line 253, in update
        widget = zope.component.getMultiAdapter(
      File "/home/runner/work/", line 104, in getMultiAdapter
        raise ComponentLookupError(objects, interface, name)
    zope.interface.interfaces.ComponentLookupError: ((<plone.schema.jsonfield.JSONField object at 0x7f6dc35c4dd0 plone.dexterity.schema.generated.plone_5_1681896458_2_2634134_0_plonista.plone_schema_jsonfield_jsonfield>, <WSGIRequest, URL=None>), <InterfaceClass z3c.form.interfaces.IFieldWidget>, '')

See Content types control panel: Add schema identifier to behavior description · plone/ · GitHub

Does the test-setup load the ZCML of plone.schema?