Freelander 1 TD4 oil light flickering when idle

Hello
Yesterday when I was in traffic light I noticed oil light flickering, so i pulled over checked oil level and it was bit under what it should be, so i added oil and drove home. But Light kept flickering everytime i was idling.
Oil looked quite liquid, but it just might be that engine was fully warmed and it had ran two hours.

Today I started it and didnt have any problems on short drive to work. But engine didnt reach full temperature.

Month ago i changed thermostat and about 3 months ago i changed oil.

Started to think oil pump, oil pressure sensor or leaky injector? I dont know much about these td4, is leaking injectors common? I mean maybe leaking injector has diluted engine oil?

Also drivers windows regulator broke yesterday

Leaking injectors can happen, but the oil level would increase if sufficient fuel was added to dilute the oil. The fuel pump can also leak, but again this will fill the sump with diesel, so the oil level will increase.

What distance has it done, and did you use 5w30 oil?

I feel 10w40 is a better choice, once the engine has passed 60k miles/ 100k kilometres.
Thin oils are only used for fuel economy, not long engine life.

Late to the party but change the sensor & see if normal service resumes.
Common on dying oil pressure sensors, flicker at idle but goes out when revs increased.