I am writing a program based on the SDL3 library and SDL3_image:

SDL_AppResult SDL_AppIterate(void *appstate)
{
    ...
    SDL_Texture* player = IMG_LoadTexture(renderer, "testplay.png");
    if(!player){
        std::cout << std::filesystem::current_path();
        std::cout << "2) " << SDL_GetError();
        return SDL_APP_FAILURE;
    }
    ...
    return SDL_APP_CONTINUE;
}

...but when launched it gives:

error: Unsupported image format