From my perspective Jon did sound pretty terrible during that private show they did in Nashville in October last year, it kinda set the expectation for me that there was not going to be any improvement in Jon's voice during the latest tour.

I also kinda think that the band's 3 week long rehearsals before the tour didn't do any good for Jon's voice, it probably did further damage to Jon's frail vocal cords. Jon probably pushed his voice to the limit during rehearsals because of the pressure of not being onstage in public for the last 2 years.

Honestly nobody will really knows because this is the reality we face, Jon's voice seems to be becoming weaker and weaker by the year.