I see from the KM’s on one of the pics that you are approaching 150,000 KM’s.
This is about the time when Carbon Deposits start to potentially cause issues. Verkokung in German... This can be normal depending on how the Car has been driven over time and the type of fuel used.
Lots of City driving not so good, spirited / Autobahn driving better.
Best way fwd is to have someone do a Borescope check of the entire EGR tract from the EGR Cooler up to the Inlet Valves with most concentration looking at the Inlet Manifold where the Flapper Valves are located that regulates the EGR flow.
Since you disconnected the EGR and it seemed to be better this makes most sense.
30 minute check and you know for sure without shotgun troubleshooting various parts which is expensive.
There is also a recall of the AGR Cooler itself due leaking Glycol and the resulting Fire Hazards... Has that been done ? Some Dealers do just that and don’t look any farther about the condition of Carbon deposits downstream.
If there are signs of heavy Carbon Deposits then it needs to be cleaned out and after that adaptations reset... but only after a thorough cleaning. Not cheap, lots of labor but unfortunately the way it is with modern Diesels, not just BMW.