JWST has 4 different instruments on it. While they all share the same focusing mirrors, but otherwise are 4 different measurement devices.
For the red dot observations, I believe this things have been measured by at least 3 of the 4 devices on board - NIRCam (near infrared camera, has very limited spectral capabilities through its filter wheel), NIRSpec (near infrared spectrograph) and MIRI (mid infrared instrument).
I cannot pretend to have the actual expertise, but it does seem vanishingly unlikely that all 3 instruments could create consistent artefacts in the same location.
For the red dot observations, I believe this things have been measured by at least 3 of the 4 devices on board - NIRCam (near infrared camera, has very limited spectral capabilities through its filter wheel), NIRSpec (near infrared spectrograph) and MIRI (mid infrared instrument).
I cannot pretend to have the actual expertise, but it does seem vanishingly unlikely that all 3 instruments could create consistent artefacts in the same location.