Security is a moving target. Stand still and you become insecure. That's too much liability considering that Member Tools holds personal information.
Most likely, the developers were pushed into this by external factors. Perhaps the older versions of Android lack a security protocol required, and prior ones were now insecure.
It should be noted that Android 7.1 was introduced on October 4, 2016 and last patched on October 2019. It would certainly be nice if operating systems were supported for longer, but that's not a battle the church is willing to spend resources to fight.
Check with your service provider to see what kind of deals they may have. Be open to "pre-owned" or "web only" deals. As a bonus there's odds you'll find your photos will be much sharper with better color.
Have you searched the
Help Center? Try doing a Google search and adding "site:churchofjesuschrist.org/help" to the search criteria.
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