For Qwen 3.5 0.8B presumably you're running it unquantized, because it's so small. Get at least the Q8 of Gemma 4 12B with the F32 mmproj and use an f16 kv cache.

Then run it with the latest llama.cpp that contains the Gemma 4 12B unified bug fixes, using --image-min-tokens 560 --image-max-tokens 2240 --batch-size 4096 --ubatch-size 4096 --temp 1.0 --top-p 0.95 --top-k 64 --jinja

It's understanding far more complex things for me and can reliably handle tiny text, so it should be easily understanding an image that only contains the text "This is a test".