> None of them can explain what made them change their mind on this short time frame in spring 2020. Was there new knowledge? A break thru experiment? They refuse to say.

Again, this isn't true. Plenty of them have explained it. Just not up to the standards of the conspiracy theorists. This goes beyond the "lab leak vs. natural origin" debate and is now, what, including American scientists in covering up the lab leak to aid the Chinese?

Spell out specifically what you are implying here.