Yes. On a tripod, lens-based image stabilization/optical stabilization can cause blur or a ghosted double image instead of preventing it. Stabilization works by moving lens elements to counter camera motion; when the camera is already steady on a tripod, the system can end up “chasing” tiny vibrations or even its own corrections. That can introduce movement during the exposure.

In your case, turning IS/OS off solved the problem, which matches Sigma’s own guidance for some lenses: do not use stabilization when mounted on a tripod.

A flash shot can make this more noticeable, but the flash itself is not necessarily the root cause. Flash settings can also change shutter speed depending on exposure mode, so it’s worth checking that your shutter speed and other exposure settings were the same when comparing shots.

Practical takeaway: when shooting on a tripod—especially macro work—turn off lens stabilization unless the lens specifically supports tripod use with stabilization enabled.