Mikrotik. The provider is complaining about an arp attack. What is the robbery?

Question

Mikrotik

Everything, actually in a subject.
RouterOS v6.44.3
Hap ac2(RBD52G-5HacD2HnD-TC)
On the interface from "suspicious" arp enabled and loop protect default. The latter, I suspect, in vain.
Perhaps the "local network only" has not yet been set in neighbors discovery settings.
Ps from the strange - recently, phones sometimes "wrote" "connected to wifi, without connecting to the Internet." But turning off the wifi on the phone always solved the problem.
UPD: The case turned out to be in Loop Protect. I removed it and the provider says that everything is ok.

Answer 1

Ask your ISP what the arp attack is. Take a PCAP dump from the interface, take a look just in case.

Answer 2

proxy-arp on local interface/bridge?