LinkedIn has several wide image placements, and their dimensions are not interchangeable. This page prepares a personal profile background. A company Page cover has a different shape and its own upload guidance, so using one file for both can crop the artwork unexpectedly. Decide which profile you are editing before exporting.
LinkedIn recommends 1584×396 for a personal cover image and lists JPG or PNG files smaller than 8 MB. The 4:1 shape is very wide. A normal camera photo may lose much of its top and bottom, so choose an image whose useful content already forms a horizontal band.
Think about the portrait and the text placed around the banner in the profile interface. Keep essential information away from regions that could be obscured. A background can work well as a clear photograph or a restrained brand graphic without repeating every detail from your headline and contact section inside the image itself.