Possibly Voorwerp or afterglow from i-g

[William]

https://www.legacysurvey.org//viewer/?ra=223.6632&dec=-4.7526&layer=ls-dr9&zoom=16

[tombickle]

Disappears in DR10. Likely some sort of artifact.

[William]

if something looks too good to be true, it probably is - no great surprise really