Even before COVID it is necessary to clean your phone periodically. I use 99% because it evaporates almost immediately. 99% was hard to find even before COVID 19. It is pretty simple. Here is how I do it.
Apply to a microfiber or other cloth that won’t scratch the phone and then clean all surfaces except inside the charge port, etc. The only way to do it wrong is to submerge your phone or dump it in the charge port or something.
Here is what Apple says on the matter. If anything Apple says contradicts what I have said your Mama Apple is right.