WP CLI and version control

We use WP CLI during our deploy process to fetch plugins and install them.
It works by specifying a particular version number of the plugin that we have tested and is known to work correctly but we are having problems with the Ultimate Member repository.

It seems that whenever a new version of Ultimate Member is released to the wordpress repository, the previous versions become unavailable. As we need to thoroughly test all our plugins before updating, we can not always just use the latest version and need to have a known version being available.

We do not see this issue with any other plugins that we are using. Each time a new version of Ultimate Member is released then WP CLI reports a 404 not found during the attempt at fetching any version apart from the latest.

I am not sure how or why this is happening but it seems to be related to how the Worpdress repository for Ultimate Member is managed.

With a continuous deployment strategy this issue becomes a major problem in the continued usage of the Ultimate Member plugin. Again, ultimate member is the only plugin we have this issues with. Other plugins keep previous versions available which allows us to control the point at which we upgrade to the latest versions and allows us to ensure full compatibility and working order.

Please advise on whether you will change this current process and ensure that previous versions of the plugin will continue to be available through the Worpdress repository so that we can use WP CLI to fetch and install specific version numbers and continue to keep our site maintainable and reliable.

Thank you
Phil W