Do you have your PlayStation 5 sitting vertically or horizontally? Until recently, this was a purely aesthetic issue, but it was reported just a few days ago that keeping the PS5 in a vertical position could lead to irreparable damage through liquid metal leaking.
However, it seems that this might not be the case, as YouTuber Spawn Wave has released a video stating that the PS5 is built with a barrier created by Sony to stop the liquid metal from leaking all over the console.
<social>https://youtu.be/wzN-qSrHsCw</social>
If the liquid metal does leak, this is most likely going to be due to an error with the barrier and the console rather than the position you put it in. Considering Sony's marketing for the PS5 had it mostly standing upright, it would be strange if that position was problematic with the console.
There doesn't seem to be a concrete answer on if your PS5 standing upright is bad for its health, but unless you're planning on pouring liquid metal inside the console or breaking the barrier that holds it within the PS5, you're probably good to keep it standing proud.