Tor guard nodes seemed to be under attack but the devs aren't really engaging with it publicly, at least. It happened to mine and I had to switch it to a middle relay. No problems now.
https://forum.torproject.org/t/tor-relays-shutting-down-my-4...
People say that even running a middle or guard node can get your IP blacklisted. I don't have personal experience of this because I don't use my home IP for regular use, just for selfhosting. All the other devices run on a network wide commercial VPN so if it did happen it wouldn't be an issue.