I can't have one as I have cats, but they look lovely
I've never heard of that, now wondering how are salt lamps detrimental to cats? No probs, have googled. It looks as though it's one warning that's been taken up and circulated online from 2019.
I've got loads of salt lamps all over the house, one is over 20 years old, there are electric ones and t-light holders and several pet cats have passed through here in all that time, as well as quite a few hand-reared feral kits too, but I've never seen one of them take any interest. None of my cats have ever licked one or shown any inclination to, whether they are lit or not. I have some on the hearth and kitchen windowsills and surfaces. Current dark duo are 8 and 9 years old.
Large lumps of Himalayan salt as 'salt licks' are also prevalent in stables and fields for horses and cows, way before salt lamps were even heard of. Most farms have feral cats and usually domestic ones too. I'm surprised this hasn't been publicised widely as a source of feline toxicity years ago.
By all means be careful and if you're concerned, put a salt-lamp out of a cat's reach, but please don't treat them as though they are something that's definitely going to poison or kill your cat because in my experience, that's not true.
You could get a glass cylinder tube that's open at both ends to put over a salt lamp t-light, tall enough to keep a cat off it 24/7.