Let us consider an infinite charged plane sheet with the surface charge density σ.
Surface charge density, σ = charge/Area = q/A.
σ is the surface charge density on both sides of the sheets.
Electric flux at both sides of the sheet is the same as the equidistant from the sheet.
The number of electric flux passing through both sides of the cylinder is equal.
Reference Source:
[1] Electric Field, Flat Sheets of Charge. Gsu.edu. Published 2022. Accessed February 26, 2022. http://hyperphysics.phy-astr.gsu.edu/hbase/electric/elesht.html#:~:text=Electric%20Field%3A%20Sheet%20of%20Charge,the%20charge%20sheet%20is%20used.
[2] Electric Field Intensity Due To A Thin Uniformly Charged Infinite Plane Sheet. BYJUS. Published April 29, 2021. Accessed February 26, 2022. https://byjus.com/physics/electric-field-intensity-due-to-a-thin-uniformly-charged-infinite-plane-sheet/
[3] Pandey, DC. Understanding Physics for JEE Main and Advanced. Meerut, Arihant.