Why are my horizontal images on Instagram in a bad quality?

Hello everyone, I have a bit of a struggle posting my horizontal pictures on Instagram. The quality gets so bad. I've tried to search on the internet for the ideal pixels and ratio but it still doesn't seem to work.

I also prefer using white borders around my image, but even when I upload my photo without the border it's still the same bad quality.

Is there anything else I can try out or are there any more advanched and technical tips to fix this?

Example of what the image looks like when I upload it.