From what I can tell in https://gerrit.wikimedia.org/r/c/operations/software/thumbor-plugins/+/785127 (most of?) the code has been basically copy pasted from https://github.com/thumbor-community/core/tree/master/tc_core and the headers haven't been maintained.
# Copyright (c) 2017, thumbor-community
has been replaced with
# Copyright (c) 2022 Wikimedia Foundation
Technically AIUI the MIT license allows this, but it just feels poor practice to not attribute where it came from (in the commit summary, but it's too late for that), and it's hardly any effort to keep the original copyright lines, even if we then add our on own on top.