At this point I don't think anyone should be unduly concerned about this bear. The link (from that particular pharmacy) actually says this:
"Pfizer, the sole supplier of Provera tablets, are experiencing manufacturing delays, and are out of stock of the 100mg tablets until week ending 8th November 2019 and there are insufficient amounts of other strengths to bridge the gap in supply. At present it seems possible to import supplies of unlicensed medroxyprogesterone acetate 100mg tablets."
So - firstly there is a generic MPA available and secondly this high dose is not used for HRT but as a treatment for other conditions - the dose for HRT is 2.5 mg or 5 mg.
Hurdity x