Recommended range is 0.2 - 1 strength .
The LoRA give REALLY strong effect. I would recommend starting low ~0.6 and adjusting according to your preferences. If you don't use other LoRA you will have significat difference in the composition and colors compared to stock Flux even as low as 0.2 .
I would not recommend using it above 1.3 strength.
All images in the Showcase Gallery were created using this workflow and the Flux Q4 Dev model on a machine with 8GB VRAM:
https://civitai.com/models/658639/super-simple-gguf-quantized-flux-lora-workflow