Hello everybody,
So I've had my 2000 528i for about 2 weeks now and I've noticed a few issues that i have not been able to figure out.
A bit of info about my car: my headlights are different. Passenger side is the correct Depo HID light and the driver's side is Hella brand but it does not fit correctly on my car, leaving a gap of about an inch between the side of the light and the fender.
The tail lights look to be aftermarket Depo brand made to look like the facelift Hellas.

First issue: Turn signals-
When I use my turn signals during the day, they work fine without any issue. But in the evening when i turn on my lights, my turn signal begin to blink fast, now i know that means that one of my bulbs is out, but the weird thing is that they are all working. Front, back and side signals are working. It does this on both sides and only when my lights are on.

Issue #2: Tail lights-
When my lights are on, my dash will show an issue with my tail lights, first the right and then the left. Sometimes the error will turn off but will come back within a few minutes. I checked the tail lights and there is nothing out back there either. I have noticed though, that when i turn on my car, lights on or off, the brake part of my tail lights will flicker for around 2 seconds and then stop. I have tried cleaning up and greasing the bulbs and no luck.

If anybody could help me diagnose the issue, i would be very grateful. Thanks ahead everyone.