In all honesty for years I had one in my small home office, and every time I printed something I could smell it in the room afterwards for an hour, sometimes even getting headaches from this. Switched to inkjet a few years ago and will never look back.
Samsung ML-1630. I had it for a really long time. I had opened it up to solder the page counter to ground so it always thought it was on page 0, instead of demanding to replacement. And I had manually refilled the toner many times into the toner cart. But I don’t think the smell is because of that, it’s the same laser printer / photocopier smell you smell in all print shops. I believe it is small aerosolized toner particles, makes me wonder if long term print shop workers have a higher cancer rate.
Possibly ozone, generated by the corona wire - the printer will have a filter which is only good for some (large) number of duty cycles.
Very few domestic / small office printers will ever hit that number, but for a ~20 year old model, it's possible yours has. The service manual suggests it's rated for 50,000 pages (as are the drum and roller), but unfortunately isn't replaceable.
Time for a new model?
(The canonical print shop smell is ozone - imagesetters produced way more than a laser printer - together with solvent from the inks and lots and lots of stale coffee. Possibly mixed with cigarette smoke, depending on just how long ago you're talking about...)
