A bird flying past the camera lens will also look like that
Like the ‘orbs’ and ‘rods’ people see all over when they take flash photos at night
Insects flying past the lens moving significantly during the time the lens is open (even though it is fast)
None of those come remotely close to accounting for more than a fraction of the over all cases and not any for the fully vetted 5-20% that stand up to close scrutiny.