50 000 trades and no verification till now?
Localbitcoins is 5 years old, that would mean 10k transactions a year and 30 a day and this assuming he was there from the start.
From what I've heard from my favorites traders, at around ~10k euros the verification was triggered even in the past, I hit it in 2018 with only ~7000 euros but probably it must have been because of the fairly large chunks.
Nope, the first wave of KYC requirements for large volumes was put in place in April 2018.
Again I doubt you weren't flagged till now with the volume you claimed.
Anyhow, unfortunately, nobody here can help you here in this case, the only ones that can are LB's staff.