What could be the reason my skin condition has been so inconsistent lately?

I haven't even changed my cosmetics, but my skin condition keeps going up and down these days.
Some days my skin looks fine, but the next day it suddenly looks dry and dull, which worries me.
I'm not sure if the cause is due to the season or my lifestyle patterns.
I also became curious if it is normal for my skin to react differently every day, even when using the same product.
I'm also confused about whether it's right to reduce the number of skincare steps when my skin condition is bad.
Sometimes I stop myself from applying more, worried it might feel too heavy.
I'm also wondering if I should focus on soothing in situations like this, or if I should just do basic moisturizing.
Is there a skincare routine I can use to establish a standard when my skin condition is inconsistent?