If your Blueprint Class is a regular, common, Blueprint… then what you see on Content Browser are “packages” containing the “Class Default Object”.
Their Constructors are called during that little %0-100% loading splashscreen before the Editor opens in full.
(yes they will run the Constructor function and output those logs too)
However it’s possible to create assets containing UObjects that are not Blueprint Generated Classes in anyway, so that may vary by a lot, depends on the class.