Does anyone know what the bright blue on the left top corner of the picture is? It is a reflection of sorts or is it a star? If so what star?
That is Triton, Neptune's moon. The colours are false, since the JWST is an infrared telescope. Triton is an unusual object and probably didn't form with Neptune. Instead, it is likely a captured Kuiper belt object. It has a similar appearance to Pluto.
Also, the caption of the image states it clearly:
What do we see in Webb's latest image of the ice giant Neptune? Webb captured seven of Neptune’s 14 known moons: Galatea, Naiad, Thalassa, Despina, Proteus, Larissa, and Triton. Neptune’s large and unusual moon, Triton, dominates this Webb portrait of Neptune as a very bright point of light sporting the signature diffraction spikes seen in many of Webb’s images.
Triton looks much brighter than Neptune because the methane that Neptune is made of strongly absorbs infrared light. The mid-IR albedo of gassy Neptune is only circa 1% (ie, Neptune is as black as coal in the infrared) From The emissivity of volatile ices on Triton and Pluto it seems like icy Tridon's mid-IR albedo is probably like 50% (ie as grey as new concrete).