Or at least, started that way? Although we don't know the exact endgame of the cloning project in BAD BATCH and MANDALORIAN-both set decades apart-it's presumed by many fans to culminate in the imperfect clones we see in RISE OF SKYWALKER-the decaying Palpatine clone and also the force-less one who became Rey's father.
In BAD BATCH we see this started right after the Clone Wars and as the Clone Troopers were being deactivated, but it seems not for making armies but for something harder to do, creating clones with the force (or at least enough "Midichlorians" to be sensitive to it). However, although his face and body are warped by the force lightning Palpatines basically at the height of his power before the Alliance starts to form more and not at huge risk of a coup/betrayal so I'm not sure he would need a fresh replacement body right away.
Vader however is still somewhat damaged goods physically and mentally and it's clear by the time Luke shows up that Palpatine is considering him as a replacement, something he eventually succeeds with later with Ben through proxy.
So could the Tantiss project have originally been intended to make a clone of Anakin without the physical ravages of Kenobi and Mustafar? Or the lingering emotional attachment to Padme that Luke reawakens? But when Palpatine himself dies, the project suddenly is switched to reviving himself, but isn't perfect in part because it was intended for Anakin?