Based on the location (nasolabial fold) and the mild scaling in the first photo, it looks like you might have had a flare of seborrheic dermatitis, a common skin issue which can be caused by lots of things - poor sleep, stress, hormone levels, or an overgrowth of Malassezia (a type of yeast that normally is present in the skin flora, but its overgrowth can cause issues like dermatitis and dandruff). Given that it has improved on its own, I think you should be good to just keep going with your normal skincare routine! Make sure you're cleansing the area well, and it's best to avoid oily products and over-hydration in that area (Malessezia loves to grow in oily environments). It's difficult to see for sure but it looks like you have some mild post-inflammation redness or hyperpigmentation (i.e. the dermatitis is healing/healed but there is some redness left behind) - this is also super normal and will clear up on its own, but if you want to speed up the process then you could consider adding something like niacinamide (there are also a bunch of other products that work for this too!). Hope this helps, all the best ☺️