ᐅ The wall is likely absorbing moisture, causing the plaster to peel off. What should be done?

Dear construction experts,

Our house is surrounded by a very old brick wall that has been plastered and painted. On top, there are slate tiles installed.
After two winters, the plaster is peeling off in many places (see photos). We suspect that the very old wall is absorbing moisture from the ground. However, we are not completely sure.
What do you think could be the cause of this?
And almost more importantly, what can we do to save the wall?

Thank you very much in advance! I’m always amazed at how helpful everyone is here...

Best regards,
Daniel

Back then, there was probably only a bituminous coating applied before the first row of bricks. Today, I believe such walls are built on a damp-proof membrane, similar to modern house construction starting from the foundation slab. I suspect it would be more cost-effective in the long run to rebuild the wall. Trying to fix it with renovation plaster and so on is unlikely to be satisfying over time. Since the wall is not very high, I don’t see any major cost increase with a new build. Of course, this always depends on individual perspective. I wouldn’t hesitate and would consider it an investment in peace of mind.