@Debra300
I'm sure I've read here on the CC several times that guests were only able to use travel credit from COVID-19 cancellations in one transaction, so if they book a place that's cheaper, they lose the rest.
I've also had friends lose a lot of money not realising that they could only use their large amount of travel credit in one go and this was long before COVID-19.
However, I am sure most would not be aware of the link that you just posted, i.e. that you have to contact Airbnb to reactive the rest of the credit. Why do this? Call me cynical, but it seems like a way to dupe people out of money.
I am not sure if that's the official line, but it does seem to be happening.