That output merely shows the snapd version installed on the system, so its unclear if Nextcloud snap is installed!
We’re looking for something like this:
to see if the snap is installed at all.
If indeed Nextcloud snap is installed and the automatic update failed for some reason, you can revert to get it up and running again:
There are various factors that could cause an issue with your Nextcloud snap instance. Your logs may help find a probable cause. There is a good chance someone in the community has had a similar issue and knows how to resolve it.
See Getting help and post the output of the the debugging script here: