Starlink Mini as internet backup?

While not directly relevant to HA, I just realized that the starlink mini on the new $5 a month standby plan looks like a significantly better deal than using cellular for backup. I particularly want a backup WAN for Alarmo.

$175 for the mini, $5 /month, ~.4Mb/s up and down. Unlike cellular, presumably unlimited data. ATT cellular device is $200, for service, $15/month for 1G then $10/G.

Not finding a problem yet with this scheme. Using either type requires a failover capable router.