More important is exported build size, not the file size shown in windows explorer. Also scene size likely increased if you have prefabs/textures/audio referenced in that scene, FSMs alone usually are not heavy.
Depending on platform look up for optimizing builds by compressing textures/audio in Unity's import settings (selecting an asset and look at inspector) and changing other project settings

I cannot be sure that the values in the attachment below are normal.

While even audio clips are 20MB, all Playmaker values exceed 100MB in total.
The game was made entirely with Playmaker.

Hello all!
I'm looking to set up save slots to my game. My ideas are getting complicated, so I'm sure there's a simpler method that where I'm headed.
The idea was to use the save slot number as a global variable, and prefix to save and load keys. Each key would have "Slot1_" added using the build string action to every save and load call.
This means that I have to have states where I build these strings, and extra variables (slot number, key, key with slot number appended).

It would be easier if I could just use the save slot to point to another file, and leave all my keys alone. Is that a possibility?

thank you.
I'll try making it.

Since I'm developing a mobile game, every megabyte matters to me. My main menu scene is 10.5 MB, which already causes long loading times...

As you can see in the image, even a single FSM alone takes up 1 MB of space.

When I delete all the FSMs in my main menu, the size drops from 10.5 MB to 500 KB

What can I do to prevent this?

Sorry for the delay, long time i didn't get here... I hope you find a solution but in case not with my solution as I said you need to save in a separate string your cumulative string EACH time you are looping and display this one into your textbox. it's maybe that point you forget because if your looping your original string letter by letter thats the reason it's only display on the same spot because you didn't create a phrase but only letters.