Yes and no, but then you’ll run into a different issue in that your pigment effects get toned down drastically by the varnish.

Pigments can be applied dry (like you did) or wet (pigment mixed with thinner/fixer) to different effect. Either method, this stage of weathering is often the final step. Varnishing afterwards will help “lock in” the pigments yes, but at the cost of having the pigments appear more subtle. It’s not wrong to do it’s just a trade off. It’s also very common to simply leave the pigments as is, the idea being you’re not going to handle the model anymore and only display it.

As for what you did, I think you literally did wash your pigments away, or at the least some of them. It might be the photo quality but I can still see a thin layer of pigments.