You'll be surprised how many scientific papers published in reputable journals are not "properly reviewed". In many cases there simply isn't enough time or knowledge to go through every detail of a paper. One example -- if a paper says go to a github repository to look at our source code, guess how many people actually review the code as part of the peer review process? Very few. There could be serious bugs in the code that would affect the results, or maybe the code is difficult to set up and run, but nobody would notice them for a long time.
After reading my previous comments, why would you think that surprises me? I know for a fact that academics of the highest reputation do very poor reviewing. The cost of a low-quality review is basically zero for the reviewer, while the cost of a high-quality review is high. The consequences of this are not surprising.
