The length of a review has no bearing in this case.
Where those the reviews that related to Source Code Form License?
If so, they did not appear to be a review of the addon but a comment about its licence. The same texts were also posted to multiple addons verbatim.
by David Hedlund on September 4, 2017 · permalink From https://www.mozilla.org/en-US/MPL/2.0/ Exhibit A - Source Code Form License Notice This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0. If a copy of the MPL was not distributed with this file, You can obtain one at https://mozilla.org/MPL/2.0/. If it is not possible or desirable to put the notice in a particular file, then You may include the notice in a location (such as a LICENSE file in a relevant directory) where a recipient would be likely to look for such a notice. You may add additional accurate notices of copyright ownership. * Can you please download https://www.mozilla.org/media/MPL/2.0/index.txt, rename the file from index.txt to LICENSE, and put it in the root directory for your add-on? * You can copy pre-defined headers from https://www.mozilla.org/en-US/MPL/headers/ if you want to use them.