Tried searching and didn't find anyone else reporting it.
I've uploaded a video as well. Possibly making it a bit easier to see.
https://www.youtube.com/watch?v=NlcShcHc7rA
Rain on Gleba doesn't extend to 21:9 aspect ratio
Re: Rain on Gleba doesn't extend to 21:9 aspect ratio
Thanks for the report. The current rain and snow effects are somewhat of a place holder and are not screen-size aware. Given there are currently plans to make them into shaders or some simpler system I don't want to try to shoe-horn in screen size awareness at the moment. Maybe in the future if the shaders never happen, but even then I'm unsure if it's worth it.
If you want to get ahold of me I'm almost always on Discord.