ewanchic PRO said about 3 years ago on Nested Forms from Scratch with StimulusJS :
FYI, Deprecated Warning:
Please replace data-target="nested-form.template" with data-nested-form-target="template". The data-target attribute is deprecated and will be removed in a future version of Stimulus.<template data-target="nested-form.template">

Please replace data-target="nested-form.add_item" with data-nested-form-target="add_item". The data-target attribute is deprecated and will be removed in a future version of Stimulus.<div data-target="nested-form.add_item">