Both AST and Starlink are reporting speeds of around 10 Mbit/s. Those are not like the service Globalstar is providing to Apple phones for just emergency texts.

https://uk.pcmag.com/networking/151288/spacexs-cellular-starlink-hits-17mbps-download-speed-to-android-phone

From: David Lang <david@lang.hm>
To: Eugene Y Chang <eugene.chang@ieee.org>
Cc: Frantisek Borsik <frantisek.borsik@gmail.com>,  Dave Taht via
        Starlink <starlink@lists.bufferbloat.net>
Subject: Re: [Starlink] SpaceX/Starlink says it's ready for a fall
        satellite-to-cell service with T-Mobile
Message-ID: <o29q52qp-p7p8-711q-q0ns-57or8866854n@ynat.uz>
Content-Type: text/plain; charset="iso8859-7"; Format="flowed"

This is a fallback that will only be if there is no other coverage, and will be
a poor data rate.

I would expect that the impact to the phone battery would be less than the phone
continually searching for a tower

Also, SpaceX has pushed back, according to them this isn't observed interference
with their signals, instead they reconfigured a satellite to the direct-to-phone
frequencies and were able to detect them

we'll see what the real story is.