There is a long history of "discoveries" where the effect is very small - always at the edge of the measuring capability.

A famous one was "polywater" - water that appeared to remember a characteristic (don't remember which) no matter how highly diluted. This made proponents of homeopathy happy, since that weird system claims that the more dilute a solution, the more powerful the effect.

Polywater was discovered to be a result of a minute amount of contamination from the extremely well washed glassware into the extremely pure water. In other words, it was not a real effect.

Then along came "cold fusion." The experimental apparatus was sufficiently simple that I decided to try it, purchasing heavy water, platinum, palladium and some glassware (I used to work as a research lab technician). Cold fusion was discovered when the Internet was still primitive and not publicly available, but my company had (slow - batch based) access. So I was able to join a mailing list of people, many researchers or experimentalists, analyzing this and doing experiments.

Before I could get the palladium formed the way I wanted it (it has a very high melting point and is hard to work with), I read the original paper (finally) and criticisms. It was clear that the apparent energy gain was greatly magnified by the use of the subtraction of two very close measurements in the denominator of the formula. But... other issues were more important. The test tubes were open to air, which meant the heavy water was rapidly replaced by ordinary water, so the effect wasn't due to the presumed fusion of deuterium. But this also meant that the amount of energy in the system was not measured well - they had to estimate the losses due to these open cells. There were several other experimental issues.

I go into this detail because this is what happens with these questionable devices. The experiment is intricate, with the possible errors likely making impossible to measure the tiny effects claimed. And this experiment was first done by eminent electrochemists, giving it more credibility.

But as others built better apparatus, most were unable to replicate the effect.

It is clearly not real - especially as it violates fundamental physical principles. Physicists say that extraordinary results require extraordinary evidence, and they say it for good reason. Here, the evidence was lacking.

If you go back to this "antigravity" - it has shown up in various experiments, all very similar, and all sharing the characteristic that there is a lot of energy put into the system, and the effect is a microscopic fraction of that energy.

Finally, the patent office does not have the ability to vet these things. They issue occasional patents on nonsense devices, just as they (improperly) issue a huge number of patents on obvious "innovations." I have patents and experience with how they are drawn up and how they are evaluated. The main thing the PTO wants is uniqueness and non-obviousness. They fail on the latter). They cannot determine if the invention actually works as claimed.

So... I think this effect is simply experimental error. This is not unusual in science, but sometimes, if those errors appear to show some almost magical result (anti-gravity, perpetual motion, room temperature fusion with energy gain), then they attract a lot of attention, and lots of articles are written.