Important point.
Pretty sure radar can be "spoofed" and technology seems to be racing to where visual mages can be as well.
While this is perhaps a possible explanation in some of these ‘encounters,’ it’s important to fully understand exactly what happened during that now famous 2004 Nimitz encounter (which then routinely happened on Eastern seaboard cruises from 2017 to 2019).
These objects were detected using disparate radar systems. That is to say radar systems that use different radar bands and wholly different radar technologies. In fact, the Nimitz had just installed the latest generation of fire control radar when they encountered all this activity.
Not only were there different radars in use, but they were being emitted from varying platforms, from the carrier to Ticonderoga/Aegis cruiser and Arleigh-Burke destroyer as well as an AWACS and the F/A-18/Ds themselves. It’s important to note that the F-18s couldn’t detect the objects until they were almost on top of them and the Marine F-18s, which used (at the time) the older generation of radar could ‘see’ them only intermittently, if at all.
In 2017, after another upgrade to the targeting pods that hang from the wings of the F/A-18s, the Hornet drivers had a much easier time tracking the objects.
Also, not only were the objects tracked using a variety of radar, but they were also tracked using a targeting system that is augmented with infrared imaging. So, they were seen optically (by the pilots), by a variety of radar systems and by gun-cameras primarily using infrared.
Whatever they were, they were physical objects, not electronic aberrations.