I would just caution...directly from the Q and A for the 2022 benefit changes :
Q: If I retire in 2021, could my benefits still be cancelled at a later date?
A: AT&T reserves the right to change or end any and all benefit plans at any time and for any reason. This includes before or after you retire or leave employment.
You may keep your subsidy for a year or 2...BUT THEY WILL pull that away from you. If you're in your 50's, your chances of making it to 65 with subsidized healthcare are miniscule.
If you fall for this, you're Charlie Brown and you're falling for it with Lucy holding the ball yet again. They want you off payroll, and this is just a new tactic to accomplish that.
You're going to need a solution for healthcare in a couple years anyway. They're not going to honor their commitment; and they're basically telling you that now.