How do I fill these gaps in the sliding patio doors??

There is a gasket you could get that will stick on there take a picture and take it to Home Depot and show a associate what you need they will help you

DIY stores will have gasket to cover this area, if not contact the manufacturer.

The manufacturer may have a fix for this, otherwise, check in your home improvement store for a gasket.

The Draft Sealer is a 3" wide, 1/16" thick heavy duty rubber weather seal that has a peel back, self-adhesive strip. Use it to seal the gap between your sliding door and the fixed (non-sliding) panel. When you are using a Patio Pet Door/Insert, the sliding door does not seal with the fixed panel. This creates a gap that bugs and drafts can come through but not sure if this is the right item for your situation but worth checking out.

That's a strange thing for a manufacturer to do. Do you know who made them? If so, contact them and ask them what fix they have for that.

You would need to contact the manufacturer tofix for this. Or you can visit your home improvement store for a gasket.

Here are some examples of the weather stripping for sliding patio doors that others have already suggested:

just add a weather seal gasket on the bottom you can find them at any hardware store

Home Depot and Lowes sells self adhesive gaskets sealers in the door section. They come in different widths so measure the gap. It is very easy to install.

Hello, you should be able to find a good fitting gasket at you local home improvement store, bring the picture with you and see what they can do for you.

i would for sure contact manufactures because that shouldn't be there

I thought these openings were to facilitate spraying lubricant