Top or left ss is what it should look like, but after updating the icons got messed up, changing values did not help, these screenshots are before and after the update on the same exact smallest width which is 384.
What you "used for months" is irrelevant, every OS is dynamic, especially MIUI.
What you're used to could very much change in the near future. No, you can't change anything back - downgrade the ROM if you want.
By the way, if you're playing with "Smallest width" that is solely your concern, Developer options are not "user preferences" - those are tools meant for testing and development.