I could tell you why some orders took longer and some still came within 2-3 weeks (pretty standard coming from int'l). I'm not going to say anything here, nor will I be too specific, but let's just say things have been getting figured out how to best work within the new system of recent changes due to various world events. Things aren't always as simple as they seem these days. USPS (along with many other countries post services) put an explanation on their site that all packs were being held and inspected, and to expect much longer delays, especially from certain countries.
This was a pretty limited issue that unfortunately happened to drag out for a couple months. It did not affect all orders, in fact it affected only a small percentage of orders. Of course you only hear about the bad experiences. No one posts when their packs come in after 9 days, and order was 100% correct. Only if an item was missing or an order took "too long" (<-subjective term), do people post.
Things should already be back to normal. It seems they are indeed from recent responses. People are getting stuff now in normal times.
In short it wasn't their fault. Some things happened that were out of their control and it overwhelmed them a bit until they started to get it under control. Everything has either been fixed or is being fixed. RxHealth was not alone in this either. Several places experienced the same thing.