If it is in a mod that you are using you can simply use the Add Icon Size mod until it gets fixed. https://mods.factorio.com/mods/darkfrei/_IconSize
If you have to fix it manually, then you add
icon_size = 32,
anywhere a icon is called, adding it below flags helped prevent a bug for me so my code looks like this
icon = "My_Tree_Mod/graphics/tree-sapling-icon.png",
flags = { "goes-to-quickbar" },
icon_size = 32,
I hope the icon_size bug becomes a distant memory for you :)
