Probably a bot. The IP ranges belongs to Amazon:
Quote
NetRange: 3.0.0.0 - 3.127.255.255
CIDR: 3.0.0.0/9
NetName: AT-88-Z
NetHandle: NET-3-0-0-0-1
Parent: NET3 (NET-3-0-0-0-0)
NetType: Direct Allocation
OriginAS:
Organization: Amazon Technologies Inc. (AT-88-Z)
RegDate: 2017-12-20
Updated: 2018-03-30
Ref: https://rdap.arin.net/registry/ip/3.0.0.0

NetRange: 18.128.0.0 - 18.255.255.255
CIDR: 18.128.0.0/9
NetName: AT-88-Z
NetHandle: NET-18-128-0-0-1
Parent: NET18 (NET-18-0-0-0-0)
NetType: Direct Allocation
OriginAS:
Organization: Amazon Technologies Inc. (AT-88-Z)
RegDate: 2018-06-29
Updated: 2018-09-19
Ref: https://rdap.arin.net/registry/ip/18.128.0.0

NetRange: 54.72.0.0 - 54.95.255.255
CIDR: 54.72.0.0/13, 54.80.0.0/12
NetName: AMAZON-2011L
NetHandle: NET-54-72-0-0-1
Parent: NET54 (NET-54-0-0-0-0)
NetType: Direct Allocation
OriginAS: AS16509
Organization: Amazon Technologies Inc. (AT-88-Z)
RegDate: 2013-11-25
Updated: 2013-11-25
Ref: https://rdap.arin.net/registry/ip/54.72.0.0