After booting wayland compositor backlight is displayed as 27%

[h3xOo]

I'm using river with i3bar-river, which handles also i3status-rust. In river's init file I have

# rest of config
riverctl spawn "blight set 10%"
riverctl spawn i3bar-river

And in i3bar-river's config.toml

command = "i3status-rs"
# rest of config

But when I login and start river, backlight is always displayed as 27%, even though really it is not. When I change it (with keybind, for example), then i3status reacts and shows real value

Real	Displayed
10%	27%
Now increase brightness by 5% with blight.
15%	15%

[bim9262]

What command are you you using with your keybindings to change the brightness, blight as well?
Do you see the same behavior if you swap the order of the spawns?

[h3xOo]

Everything backlight-related is mapped to blight. And essentially, after bar spawns, there's a few seconds before it notices any changes (if I spam increase/decrease backlight, then it's not updating).
Audio (pulseaudio) also has delay, but shorter, and spawns at 100%, but after 1-2 seconds it gets together and updates to real value.

And yes, I tried changing order of spawning, but it didn't help.