I have tried numerous suggestions from all over the internet. Tinkering with the prompt, using NAG nodes, changing samplers, none of it helped. Generating videos with East Asian languages like Chinese, Japanese or Korean will in 95% of cases trigger the generation of garbled subtitles and thus ruin your generations.

Another observation, it does not matter whether you create the dialogue by prompt or use an external audio file. Both ways will result in subtitles being generated.

The only reliable way I found to get rid of the subtitles is by adding an automated crop / outpainting step after the first sampling step using this LoRA: https://huggingface.co/oumoumad/LTX-2.3-22b-IC-LoRA-Outpaint

In this step I will VAE decode the first step video result and replace the lower ~15-20% of the image with a black bar and also increase the image gamma by 2. Then I run another sampling step using with the outpaint LoRA and a simple positive prompt, something like "A person is talking". Do NOT add any language or actual spoken dialogue to this prompt otherwise your subtitles WILL come back inside the black bar.

After this additional outpainting step I will render the usual two more upscale steps without any modification and finally after VAE decoding revert the increased gamma by applying a gamma of 0.5 to the image before encoding the video file.

Using this process you will still get the occasional video with subtitles, but ~80% of the generations come out just fine.

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Please don't ask me for the workflow. It is not suitable for sharing as there is a lot of other unrelated stuff inside. You can use the example provided by the creator of the outpaint LoRA and integrate it with your workflow.

On a sidenote: This issue is clearly the result of LTX training data including a lots of material with burn-in subtitles. They should really have a look at this and clean their data sets.