Lines look jaggy in Illustrator

I have litterally just had this and fixed it for one file. Sometimes I find (especially if I have used the eye dropper for a colour grab) the vector shape edges will look a little sharp and pixelated. Sometimes even having the old colour (say black) just showing on edges. IF i remove / clear the the apperance stack it removes this effect. THIS ALSO FIXED an issue where pathfinder was making gaps that I just had on one artwork. This appears to work even on a basic stack with NO effects other than an empty stroke and a single Fill. I also notice sometimes if the colour is wrong if you move the fill to the top of the stack over top of the empty stoke it can solve it too.

What you see is perfectly normal, and unavoidable, especially with lines that are nearly horizontal or nearly vertical, and it depends on the resolution of your export. Of course you can export at higher resolution (say 600ppi since your file is essentailly just line work). Why you don't see it as much on your screen is because Illustrator is rendering your vector lines to the resolution of your screen, and that changes at different zoom levels... e.g. when you zoom in, the BETTER it looks, but even at 100%, there's pixelization going on.

You could turn anti-aliasing off, but then you will see VERY jaggy lines, so anti-aliasing is doing its best to improv the overall look.

Enes,

It also looks normal to me, apart from certain inaccuracies unrelated to the question, see below.

"today I make this drawing and the lines look in a weird, jagged way."

If it is only happening with the current document, it could be corrupt, and you can try to copy and paste the artwork into a new document, all in one go or in parts.

Concerning inaccuracies: there are some mismatches between certain paths at the front, bottom, and rear.

What is the thickness, strokewidth of your lines? If they are too thin, there may not be enough pixels to display them.

I don't see anything unusual there. There are pixels in your monitor.