Hi Sally,
each Google Chrome update supersedes the previous one and this supersedence relationship is 1:1 so update N supersedes update N-1 but there is no direct supersedence established between N and N-2, N-3, etc. (only indirect through N-1, etc.).
Updates between Chrome-228 and Chrome-234 (in this example) were marked as no more downloadable (as they were replaced by newer version of Chrome by Google) so they were removed from datafeed and supersedence chain between Chrome-228 and Chrome-234 was broken (resulting in Chrome-228 displaying in reports instead of being hidden as superseded). Actually in this case Chrome-228 needed to be marked as no more downloadable as well.
This was brought to the content team and they plan to fix it by marking all outdated Chrome updates as no more downloadable - should be released soon.