The accuracy of the landing point during RTH does vary, 1 to 2m would not surprise me, though I think my Mavic Mini normally is within 1m. 5m does seem a bit out.
Are you certain it is setting a homepoint as it takes off and is your takeoff vertical?
Normally I would use RTH only to bring it more or less overhead and then I would land it manually.
At home my Mavic Mini rarely has a good GPS lock at take off and then sets the homepoint in flight, as it gets a better look at the sky. I generally send it up and only a short distance away until it tells me a homepoint has been set i.e. it has sufficient GPS satellites. Then I either bring it back over head and reset the homepoint or bring it back, land it and quickly take off again 'whilst' it still has a good GPS lock.
Because I have some times had quirky homepoints set I generally test it onec it has been set by flying the drone to beyond the minimum RTH distance and then initating an RTH to see if it does come back to overhead.
With regards to "I look at the bottom sensors, 1 lights up for a moment. other doesn't." uum I do not have a
mini 2 but going by the manual the bottom sensor are Infra Red, can you see Infra Red? I can not but my phone's camera can. With the motors off the phone sees no 'light' from either lens of my Mavic Mini. In flight the phone sees 'light' from only one lens. Others need to chip in on this but I would be surprised if the
Mini 2 differs from the Mavic Mini in this respect.
Regarding height, if you mean that the on coming into land the landing point appears to be not at 0, zero, height, that is fairly normal and the 'error' can vary. I rarely pay attention to that.
The height is set by measuring the air pressure and as the latter can vary during a flight it is not unreasonable for the apparent height of the landing point to be slightly out. There may also be some drift in the sensor.
This is one reason why it is a good idea to allow a reasonable clearance, height wise, between any object in the RTH flight path and the drone, I normally add 7m or so to clear a tree at home
