Regardless of weather sealing lenses will get dusty if they breathe. If any outside lenses move the internal volume of air must change and that means air is being exchanged with the outside.
1: https://www.lensrentals.com/blog/2011/08/the-apocalypse-of-l... 2: https://www.lensrentals.com/blog/2019/04/removing-fly-from-w...
First, hepa filters tend to block flow of air A LOT. Lens designers strive to get lenses to focus as quickly as possible. Any blockage of air would necessarily make it very difficult for the lens to breathe quickly.
Second, dust particles in the lens do not affect the image nearly as much as you would think they do. Just look at this pic: https://www.lensrentals.com/blog/2008/10/front-element-scrat...
And if the seal fails then you'll get a lot of dust inside.
The dust that gets inside from breathing while zooming rarely affects image quality to any meaningful degree. Excessive humidity can lead to fungus growing on the glass though, which really can ruin your contrast. It's normally good enough to keep your lenses in a box with some silica desiccant during summer to prevent that.