I don't see we ever had support for this SVG feature in svg2pdf - can you provide sample input and output to prove your point?

Here two examples:

• latest versions of svg2pdf and jsPdf: https://jsfiddle.net/ladypops/xpvt214o/896964/
• svg2pdf v1.1.1 and jsPdf 1.3.2: https://jsfiddle.net/ladypops/xpvt214o/896963/

In console you can open the link and see the difference.

I've tried a lot of combinations of different versions and it works only with 1.1.1.
Any ideas?

Thanks for the example. That's actually a coincidence: Up to 1.1.1 we obviously did not scale the strokes at all. If you remove the vector-effect in the 1.1.1 example you get the very same results and the lines do not get scaled (although they should). In a way this was a bug and you benefitted from it. The resolution to your problem would be the implementation of the feature, rather than fixing a non-existant feature.

Oh, thanks :)
So will this feature be implemented in the nearest future?
Or where can I control(or remove) stroke scaling?

Since we do not need to implement the whole vector effects API for the "non-scaling-stroke" vector effect, this can be implemented quite easily. We might consider it for the next release.