on my Ubuntu machine fonts are scaled with 200%. Launching an sdl app sets font scaling to 100% after quitting so fonts are quite small. How can I reset to the configured font scaling after my sdl app quits or how can I prevent sdl from changing font scaling?
uname -a: Linux bb-ubuntu 5.19.0-45-generic #46~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Wed Jun 7 15:06:04 UTC 20 x86_64 x86_64 x86_64 GNU/Linux
sdl2-config --version: 2.0.20
Might be good to backup and update your machine to a newer version of Ubuntu. That version of SDL is from January of 2022.
Built current version myself: 
sdl2-config --version: 2.27.1
Still the same behaviour.
 SDL2/Installation - SDL Wiki
Think I have found some kind of workaround: Creating a fullscreen window in full screen resolution with SDL_WINDOW_FULLSCREEN does not change scaling (as long as you don’t change the screen resolution).