+add as contact
If this is an active site for arranging meet ups, and I've always found it to be, it's no surprise it's very quiet now when lockdown and tiers make fun virtually impossible. So, plenty of people will have not bothered logging on.
I don't think it's the complete answer as I've seen a steady reduction in numbers over the last five years.
Whether it's the enhanced security, I don't know, but it can't have helped. But, there must have been a good reason for introducing it.
The acid test may be when the virus is not a major factor in all our lives.