Under certain atmospheric conditions it may be possible to see further

https://en.wikipedia.org/wiki/Mirage#Superior_mirage

I wonder what the maximum you can ever see is due to atmosphereic fog. I suspect it's less than 538km.

The site has photos listed for up to 381km, although the link for that one is broken.

This one is the longest: https://beyondhorizons.eu/2016/08/03/pic-de-finestrelles-pic...

Fog is definitely a factor.

This is why some microwave radio antennas point up. They bounce the signal off the troposphere to pair with a receiver farther away than the horizon. https://en.m.wikipedia.org/wiki/Tropospheric_scatter