Hi Gudrun.
This problem has nothing to do with Joomshaper products. It belongs to the field of knowledge of graphics and screens. For devices with x2 pixel ratio , what are Apple devices requires images one and a half to two times bigest for high-quality displaing. Or images in SVG format.
Just redraw your logo in SVG using Adobe Illustrator or any other vector editor.
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Hi Mehtaz. You should know such simple things and understand them from the first user appeal, instead of asking for access, which will not decide anything. Increase the quality of your work. 1 week to solve such a simple issue, in my opinion it is inconceivable