Since the Tor directory authorities are no longer removing such undeclared relay groups
and I feel bad about sitting on this list without doing anything with it
I'm posting it here for your information.
This is a set of over 600 Tor relays that got added since 2020-01-29 on a limited set of hosters.
They have some similarities in their sign-up pattern and properties.
Most of them are middle relays (non exit relays).
total guard probability: 3.6%
total middle probability: 10.1%
https://github.com/nusenu/tor-network-observations/blob/master/20200129-20200819_unknown_middle_relaygroup.txt
+-----------------------+----------+
| as_name | relays |
+-----------------------+----------+
| Microsoft Corporation | 254 |
| Linode, LLC | 82 |
| UAB Cherry Servers | 75 |
| <missing ASN data> | 62 |
| Cogent Communications | 44 |
| Hetzner Online GmbH | 38 |
| OVH SAS | 26 |
| DigitalOcean, LLC | 11 |
| Online S.a.s. | 9 |
| Enzu Inc | 7 |
+-----------------------+----------+