It may or may not has something to do at least with that automatic TL1, but with disable email verification too. I have these several times with same user all the time:
id: 606
username: saja
name: Saja
created_at: 2023-10-28 14:34:13 UTC
trust_level: 1
last_seen_at:
last_emailed_at:
2.11., 28.10., 12.10., and 27.9. Strange is that admin log doesn’t show any IP addresses for that user. Every other deletion for non activate accounts show IP.