The artifact comes from the DSS, the Digital Sky Survey. SIMBAD is a star catalog, and it displays sky maps from Aladin. Aladin sources the data from different sky surveys, and DSS is the one with this particular artifact.
There is a very bright star just outside the field of view. You provided three examples, and two of them have bright stars nearby, while the middle one does not seem to. Here is a different zoomed-out view of your main example:
You can see the bright star between 4° and 5° from the artifact. For this pointing, "Mellinger color" is another sky survey option. It does not show the same artifact.
It would take a lot of digging to find out exactly how they put together the data for the DSS, which used photographic plates. I can provide a guess:
These kind of artifacts get worse the closer you are to the bright object. They must have used some kind of screening algorithm to select the right frames close to the bright star to remove these artifacts. But perhaps the algorithm was only applied within 4° of bright stars, leaving your examples as rare outliers. It could be significant (in terms of the telescope light scattering) that both the artifacts lie directly to the east of the bright star.
I am at a loss to explain the middle example with no bright star 4°-5° away. It is at declination -42°, so the Moon and planets should never reach this far south. One possibility could be that there was a brief light source inside the dome during the exposure.