Angry Astronaught did a video on this that has some useful background:
https://youtu.be/kO5PMm84kmU?si=aaUJccVL24XZWLc5The idea is not new, going back several decades.
The great question is whether the milli newtons measured by Charles Buer for his exodus drive are caused by what he believes or are a systematic error in his measurements.
Dr Buer has patented his idea, but the uspto is full of patents for devices that have no practical demonstration, so that tells us nothing about the validity.
If I understand what he is claiming, he suggests that having regions of positive & negative charge, on a space vessel lead to a force away from the vessel, I.e. a thrust.
The only way that I can see this being real is if he has stumbled upon a way to either create an opposite charge in the fabric of existence (space-time) or that this electrostatic effect deforms space time enough to reduce it before his craft so that the craft falls into this deformed space-time & moves by a series of falls as in a warp drive.
No idea if it is real, but if he can demonstrate it, the cumulative acceleration would accelerate his craft rapidly as Angry Astronaught describes.
Another experiment by Dr Ning Li in Huntsville, was put in a refereed journal showing a 2% reduction in gravity above a rotating super conductor, but no one seems to have followed up the research & I believe Dr Li has passed away.
Regarding comments about perpetual motion being impossible, one can think of the hydrogen atom, one proton with a circulating electron, no external power needed, no radiation of energy as expected for an accelerating charge. It too does not violate thermodynamics as no heat is emitted, but it is perpetual motion in the quantum world. Further down one has the uud quarks within the proton, all of small mass, united by large binding energy & all endlessly in motion exchanging gluons at least according to the standard model.
I have no idea what might eventually be discovered about interactions between the quantum & macro worlds, but it is a huge field, hindered by the fact that no one understands quantum mechanics. We can use the mathematics of quantum mechanics, but understanding what happens in process like wave function collapse or entanglement is well beyond us.
Regards,