https://bitnodes.io/nodes/ unfortunately doesn't support filtered statistic (e.g. client distribution based on selected network/location) but at quick glance shows most nodes uses 0.19.x or newer.
I have had some success grouping the nodes by ASN number of their IP addresses, each ASN number indicates a data center. They look like ASN472548 for example, and it's possible to determine the location of the node based on the ASN number.
On bitnodes if you open the Networks tab you can see a grouping of all online nodes by network. The most online nodes are running on Tor network at 25.64% of the online bitcoin network, the second largest is running on Hetzner at 10.37%, the next four largest groups are evenly distributed between AWS, Digital Ocean, OVH and Linode at about 500/400 nodes each.
I think there are less Tor instances running than datacenter VMs at any given provider, because of the legal ramifications of running one. So pointing most of nodes at the Tor network might be bad for decentralization because there are a lot of underutilized hosting providers that only have a few full nodes on their datacenter. I'm running mine (it will have a long uptime) at Leaseweb NL which has just 29 nodes running on its entire datacenter.
We currently have no idea how many Tor nodes are running at a given hosting provider, because such statistics aren't available. But, with 8002 nodes not running on Tor, and 2759 nodes running on Tor, about a quarter of the network as I wrote above, one needs to think about how many exit nodes exist and are shared among the full nodes pointed to Tor.
According to the graph at
https://metrics.torproject.org/relayflags.html there are about 800 exit nodes (and according to
this 100 of these spy on connections). So that's 3 full nodes sharing the same exit node. So we really only have about 8800 unique IPs running 24/7 on the bitcoin network.
I am not anti-Tor and this post should not be interpreted as such, but even though the bitcoin network doesn't transmit sensitive info, I'd trust a commercial provider not to inspect a random VM's network traffic more than a Tor node that might be a government agency honeypot in disguise. That's why I encourage people to run full nodes on less-used data centers.