ᐅ Water pipe with limestone buildup? It’s leaking.

Good evening,

while tidying up for a viewing tomorrow, we noticed the following at the water house connection:

Since I am a complete layperson, and this "lime scale" or whatever it may be does not appear on any other part of the house connection, I thought I could ask here what this might be and whether it needs to be repaired.

Condensation forms on the pipes due to the very cold water.
It is also worth mentioning that the water in our area is very hard, measuring 19 °dH (19 °dH).

However, I thought it is unlikely that condensation alone is the cause, since no other part shows this phenomenon.
I also do not know if the condensation is dripping onto the floor or if there is a leaking joint.
Since we found a significant deposit of dripping water on the floor only beneath this connection, I assume the pipe might be leaking.
Does anyone have an assessment of this?

Can someone tell me what this is?

Thank you very much!
Kedakai

Condensation does not contain lime.
There has been a leak for a long time.
Remove, replace the seal and fitting, and that will solve the problem.