I have stub notes for people I've met, and link to them in the journal section of my daily note when I've met them; I can then check the backlinks on that person's note when I want to check where I've seen them before.

Not the OP, but I've got a "Names to remember" evergreen note in my Reference folder. Within it, I have a few headings (e.g. neighbours, or locations), and a bullet point for each person, with context that will trigger the memory. That might sound like there's a lot of structure, but it's really the act of writing it down in the first place that helps me remember.

I use Obsidian for the same purpose as the sister comment. I have a long old note where I add the name and a minor info for new acquaintances. Mine is charavterised by the environment of acquaintance, i.e Work/Town/Rave/Hobby/Online. Rarely need to refer back once ive written down.

I make a new card in a folder called People whenever I meet someone. Then I add information like email address, phone number, connections to other people when relevant.

I find engaging like this helps my memory already on its own, but if I'm ever really stuck with a name I just take a quick look at my phone. The person is usually linked to the event where I first met them or similar.