Uneven shower floor so water pools in edges. Lots of scum.
Use a cleaner called Mr Muscle for soap scum..........
for a more natural way
Heat up 1 cup of white vinegar, mix in about 1/4 cup of Dawn Premium. Not the dollar store kind, because it is too thin. When mixed, pour into a spray bottle and fill with water. Shake. Spray down the grout and let it sit overnight. In the morning rinse. If you have stubborn stains, spray again. Use this mixture a few times a week. It will keep your grout and tiles clean. Also works wonders in the toilet bowl to keep hard water stains at bay. Oh you only have to heat the vinegar one time when you add the Dawn.
Bar soap has paraffin in it that causes soap scum . Once you get it clean you need to change to body wash or gel so you wont have that problem.
I clean my tile with a mixture of vinegar and water. You can find more about that here - https://chascrazycreations.com/natural-cleaning-with-vinegar/