ᐅ Damage to the foundation base: Splash-back water or something else?

Hello everyone,

I know it’s a bit like looking into a crystal ball, but I’d like to ask you anyway:
I went to a viewing of an apartment with my brother (a two-family house). He is interested in buying the ground-floor apartment (built in 1994, with an overall condition typical for that construction year, at least on the inside).
What caught my attention on the outside are the plaster damages on the base of the wall. Could these be caused by the absence of a gravel layer and therefore by splash-back water damage, or are they more likely caused by something like flooding (the property is located in a flood-prone area)? Unfortunately, nothing is known about the original construction method. The photo shows part of the exterior basement wall.
I scanned all the basement walls inside with my crystal ball laser thermometer/humidity meter (the temperature was 9.4°C (49°F) and I still need to check the humidity). Of course, there are many opinions about these devices, but my father-in-law (a building surveyor) used one on our build, and when I checked with our device afterward, the trends were actually accurate!
Overall, the apartment is fine, but this issue with the basement and the exterior wall is giving me pause, especially since there is a gravel layer on one side and the plaster problem also exists there...
What do you think?

Photo of the exterior base

Attached is the picture of the base.

The rainwater cannot drain properly. In winter, the water expands... sooner or later, it will look like this.
Flooding and a basement together do not mix well [emoji4]
What is your question?