This is similar to the issue identified and "solved" in this post: https://community.esri.com/t5/arcgis-api-for-javascript-questions/print-export-widget-bug-button-cli...
This is still an issue with the Search widget (and possibly others). Anytime these widgets are inside a form (for whatever reason) they attempt to submit that form when the buttons in the widget are clicked. It should be a simple fix by correctly assigning the proper HTML attributes (type="button") to the clear and submit buttons in the Search widget.
Hi @BatesRambow, thanks for posting your issue here. I am investigating this issue with the Search widget.
Hi @BatesRambow, we are working on having this fixed for the next release. Can you test with next and see if the issue is resolved in your workflow?
<script src="https://js.arcgis.com/next/"></script>
https://github.com/Esri/feedback-js-api-next