Hello, you definitely need to call ir_filter(False) as you’ve done when using the IR light. The IR blocking filter is used during the day to block the IR from overwhelming the CMOS sensor (the CMOS sensor is sensitive to IR.)
As long as the lens is close to the front glass of the enclosure, you should not get any internal reflections. The annular (the ring thing in the front face of the outdoor enclosure) should prevent this from happening. Your image has a ring, but it seems to stop at the ground (yes?) The images at night are definitely of lower quality.
Edward