Why is my map zoomed in so ragged compared to what I actually drawed in QGIS

So overall my map looks the same like what I draw in QGIS. The issue is that when I zoom in, in that case 54x then you can see ragged lines.

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That is not what I need. I need high details also by zooming in. So how can I improve that.

One thing I could do is simplyfying the topojson file. But that's not a solution because I need that high quality lines because my map is often used by zooming in.

Also I could smooth the lines a bit. But already tested and still looking bad.

So how can I also by zooming in show max details. How can I tell QGIS to give more details. Or is it something of the projection? I'm using this projection: +proj=eqc +a=190493.11 +lat_ts=0 +lon_0=0 +rf=800 +units=m +no_defs. But I don't think that I can change it without loosing all right?