Hi Jerome,
Have you searched for other discussions about svg dimensions (like e.g. this one)? I see in your svg string above that you have an svg tag without ´width´, ´height´ or ´viewbox´ attributes, so you might start by adding those. I don't work with Node-RED temporarily, so can't give you an updated flow. But you can find many examples on the web, e.g. here.
Bart
Copyright OpenJS Foundation and Node-RED contributors. All rights reserved. The OpenJS Foundation has registered trademarks and uses trademarks. For a list of trademarks of the OpenJS Foundation, please see our Trademark Policy and Trademark List. Trademarks and logos not indicated on the list of OpenJS Foundation trademarks are trademarks™ or registered® trademarks of their respective holders. Use of them does not imply any affiliation with or endorsement by them.
The OpenJS Foundation | Terms of Use | Privacy Policy | OpenJS Foundation Bylaws | Trademark Policy | Trademark List | Cookie Policy