How to switch off optimization -Os

I set in my project in platformio.ini
Use STM32F4 with CMSIS
build_flags =
-O0
But in compiller logs i see … -O0 -Os … And seems GCC use last set option!
How can I disable -Os in platformio settings?
I can’t found it in settings and docs…

But it’s right there…

https://docs.platformio.org/en/latest/projectconf/sections/env/options/build/build_unflags.html

O thanks!
But i mean that see Compiller Optimizations Option in User or Workspace Settings GUI, and not found it later…

Everything is delibaretely configured through the platformio.ini file, not in VSCode Worksapce / User settings. Only that way can it be ensure that a PlatformIO project builds the same accross all 10 supported desktop IDEs.