sovos wrote:Removing the tspan tag everything works fine.
How can I do that from Inkscape?

The problem is not fact that text in Inkscape will always be inside a <text><tspan></tspan></text> structure (this is not an issue with Inkscape's custom 'Flowed text' format BTW - <text> and <tspan> are basic SVG 1.1 elements). In your example the style attribute of the <tspan> overrides the 'fill' property of the parent <text> style attribute, and any changes you apply to the 'fill' property in the style atttribute of the parent <text> object thus does not affect the fill color used to render the content of the <tspan> element (basic style inheritance in play here).

Tips when creating text in Inkscape:
Don't highlight text content when you style a text object because then the style will be applied to a <tspan> element wrapping that highlighted portion of the text (only use this you indeed want to style a portion of the text content differently (e.g. with a different font face / size or fill color) than the rest -> the highlighted portion of the text content will then get wrapped into another (nested) <tspan> element).

I see now!
The problem indeed raised when I changed the font size selecting all the text, although I didn't create the text dragging a box.

Thank you both for your helpful suggestions and time.
I wish you all a great day!
Sovos

I've struggle with the same problem for 3 days. Finally I've notice that if I remove from style the property that I wish to change, all is OK. Anyway, if you need that propriety to be defined in svg from the beginning, you could write it outside the style declaration.
For example: if I want to change by script the fill propriety of an object from green to red, I notice that style="fill:green;..." generated by Inkscape doesn't work. Then, I must delete fill:green and put it manually outside style declaration, as fill="green". Now I'm able to change green with red from a script.