If you care about security at all, you disable any previews on the lock screen. The lock screen is by definition visible to anyone without any authorization. Showing anything on it immediately destroys any secrecy. It must be obvious to anyone capable of elementary logic inference.

If you don't know how to disable it, you use your favorite search engine / LLM / knowledgeable relative to find out, and disable it.

But if you just didn't pay attention, "never thought about it", you don't care about security, and no amount of technical means would help, sorry.