This RTO is overblown. The company took a look at the situation before the pandemic compared to the work-at-home since the pandemic, and liked the situation before the pandemic. It isn't any more complicated than that.
There is the separate issue of the relocation of work. That always involves force adjustment. But relocation/RTO aren't joined at the hip.
As far as those who always RTO'ed, where you worked from is your work location for purposes of determining whether relocation and hence force adjustment applies. If force adjustment (layoff) applies, whatever is the severance goes into the calculation.
This, being an all-AT&T operation could very well turn into a cluster-situation. If so, they could halt the current plan, rethink and so forth, and this could carry on for years. Unemployment is low, so I don't see a rush.