Give the coating a fortnight of dry weather if you can. Solvent-borne alkyds need oxygen to cross-link fully; once they harden, light surface blemishes often wash off with a mild detergent.

Having said that, if you want the stain-and-varnish look to last on a deck you’ll end up chasing blemishes every season.

Two more robust options:

1) strip back to bare timber and move to a penetrating decking oil;

2) abrade, then switch to Sadolin Superdec Opaque — a flexible water-based acrylic/alkyd that copes with standing water and wears away gradually instead of flaking (three-coat system, touch-dry 2-4 h, ~30 % solids, VOC ≈ 51 g l-¹)

Extra isn’t inherently faulty; it’s simply the wrong chemistry for a walk-on surface. You can tidy the marks with cleaning and local spot-repair, but for a deck you’ll save time (and slipperiness) by moving to a product engineered for horizontal exposure – either a penetrating decking oil/stain or an opaque, high-flex coating like Superdec.

That’s frustrating. How many coats did you apply? I would prep and put an undercoat on before topcoats.

Unfortunately, flashing is always a risk with cheaper products.