It doesn’t matter. You do whichever placebos you into feeling like it’s better so you aren’t stressed about all the shit particles you’re breathing and scrubbing on your teeth.

https://www.realsimple.com/do-you-really-need-to-close-toilet-lid-before-flushing-8558163

https://www.usatoday.com/story/news/health/2024/01/25/does-it-matter-if-you-flush-with-toilet-lid-up-or-down-not-really/72321820007/