APT in Debian/Ubuntu determines packages to be upgraded by their version, but the maxscale APT repositories for Ubuntu Bionic and Focal in version 2.5 (the only ones I am tracking, this might affect every APT-packaged version) recently (Fetched by our mirror 2021-09-14, 12:00:00 UTC+0) swapped the file maxscale_2.5.15~bionic-1_amd64.deb. This will lead to "invisible" inconsistencies between installations being done before and after the swap.
Previously, I was unsure whether those republications where simple mistakes and no "real" code was touched, but this time I have, new file first: (<filename> <filesize in bytes> <sha1sum>)
maxscale_2.5.15~bionic-1_amd64.deb 52806694 39c0c1eeed27818d3c54577bc355d18cd148272d
maxscale_2.5.15~bionic-1_amd64.deb 56137056 f0ea486890755513d6073daea68257afeb253b13
The notably shrinking package size hints on something omitted from the new package that was previously, possibly by mistake, in there.
Bumping the package to maxscale_2.5.15~bionic-2_amd64.deb, raising the debian_revision part would solve this specific case. Furthermore, uploading packages that are already existent should be generally prevented, as only new machines will ever see this change.
Output of diffoscope is too large to handle for me.
Please note that I left the severity unchanged, as I do not know how to correctly classify this issue according to your guidelines - Sorry if I missed reading up on something I should have.