Looks and readability matter in writing. I always uses spaces on either side of the em-dash; looks too crowded otherwise to my eye.

I've been doing doing it that way for so long I still often use the "--" construct from way back in ascii email days.

At least I've gotten past the two-spaces after a period I learned from the typewriter. Most of the time, anyway.

In LaTeX:

- A single hyphen designates ... a hyphen.

- A doubled hyphen designates an en dash.

- A tripled hyphen designates an em dash.

<https://ladedu.com/how-to-use-en-dash-and-em-dash-in-latex/>

(I'm not aware of longer dashes native to LaTeX, though I believe doubled en or em dashes are occasionally used.)

Many Markdown flavours incorporate this, such that en / em dash usage in Markdown-authored docs should not be entirely unexpected. I believe many LLMs output Markdown which is subsequently rendered, based on watching intermediate outputs and saved sessions. I tend to adopt LaTeX / Markdown semantics elsewhere.

To me it doesn't affect readability either way, but to my American English eye the surrounding spaces stands out as extremely non-standard.