When I export an image of a loader I make to .svg code the glow effect doesn't appear later in the implementation (when we add it in the project's html/css).
I see everything else but not the glow effect I added. Actually, the image also changes a little bit when we see it on the screen. Any ideas?
If by glow you mean shadow, I've had the same issue before. But there is a way around it that I've found.
You can fake a glow/shadow using another shape and applying a Gaussian Blur, in my experience this exports just fine from Sketch to SVG.
Often, software can have effects which can't be exported in an SVG because they are not supported in the SVG format itself. This goes for other vector image editors, not just Sketch, and also includes the likes of Adobe Illustrator and Inkscape.
When designing graphics which are intended to be output as SVG, try not to rely on any software effects if possible, or only use those effects which are supported in the SVG format, and also in browsers. Simplify the design instead, or try to achieve the effect in a different way which doesn't rely on actual software effects.
