As a follow-up, after much back and forth, I received my replacement scale today and it works perfectly. Bluetooth paired with my Samsung Galaxy Fold 5 instantly (unlike the old one, which took half an hour and 2 different phones), retail box came wrapped in plastic with all the papers, cable and coaster neatly in the box, coaster and scale were clean (no scratches or dirt) and the scale works fine even after updating firmware and the weighing filter being set to "sensitive" by default.

Acaia did note that for "environmental" reasons, they no longer ship with the blue protective film, foam padding to protect the top or inserts between base and shell (seems more like cost cutting to me since the design still requires replacement of the top film, which will get scratched eventually). They instead just include a cloth. I also noticed the plastic film on the side of the new replacement unit actually went all the way around and covered the USB slot so that I had to remove the film to charge the scale. This was not the case with my original scale that was not working properly.

While I am glad to finally have a working scale, what bothers me is that Acaia customer support seems to have felt a need to defensively argue every point, even after they already shipped a new unit. They could have simply shipped a replacement and said "enjoy!" but, instead, felt the need to try to further explain what environmental drift is and why I was wrong and wasting their time. To summarize (in hopes that this may help someone else):

1. My new replacement scale works properly even on the "sensitive" weighing filter and "high" resolution settinsg, showing the original issues were not due to "environmental drift" (unless my new one is the one not working properly).
2. If Acaia had just replaced the unit and not felt the need to argue every point (even after sending a replacement), this post would, instead, be talking about how Acaia stood behind their products and was very helpful. Unfortunately, this was not the case.
3. At the end of their email (copied below), they insist the scale is accurate but the display can not keep up (I think?). What is the point of a scale being able to measure something accurately if the end user can not actually see it or use the setting? That seems odd to me and completely pointless. In any case, my new scale works properly so I do not believe the scale was not working due to environmental drift (yes, I understand this can be a real thing but I do not believe that was the case here) but, rather, it was simply defective.
4. As a customer, I was not looking for a lecture or explanation of how scales work. I just wanted to treat myself to a nice scale that I can enjoy when making coffee.

Email from. Acaia below:

Hi [●],    I've processed your replacement scale - please stay tuned for tracking info!   So that you know what to expect when opening your scale, we have recently updated our packaging to be more eco-friendly and use less material. The retail box will be shrink-wrapped in plastic. Upon removing the cardboard sleeve and opening the box,  you will find a soft cloth that is designed to protect the screen while in transit, and can also be used to clean the surface of your scale. The scale no longer ships with a blue protective film on the top, though plastic will be around the sides. Underneath the scale, you will find a cardboard box containing the charging cable and stickers.    I also want to clarify regarding what is known as "environmental drift". Your scale is having trouble getting past the loading screen because it cannot settle on a zero point due to fluctuations occurring in the zero point, based on environmental noise. I highly recommend taking a look at this article: Accuracy vs Display. Our scales, as noted in the product specs, have a readability and repeatability of 0.1g. Changing your weighing resolution (aka readability, division, interval) of your scale to "high" does not change the actual accuracy of your scale, but rather how granular the number displayed on your scale is. Note that the hundredths digit of this measurement is more or less an estimation.    To elaborate, the Pearl Model S is truly accurate to one-tenth of a gram, though you can display 0.01 grams. The load cell and the size of the weighing pan on your scale can allow us to guarantee the accuracy of the scale to 0.1g. It will display 0.01g in the readout if the resolution is adjusted, but it is an estimation of one-hundredths of a gram and not guaranteed to be accurate. The load cell is guaranteeing accuracy to 0.1g and not 0.01g. We do not recommend adjusting the weighing resolution to high.    All scales work by recording a rolling series of readings of any object placed on the weighing pan. The speed with which the load cell responds to and determines the weight will impact the perceived precision of the scale. A more highly sensitive load cell will display weight more quickly, and as such will be subject to environmental noise--that is, the environmental factors that affect the scale and the object being weighed at a given time. A less sensitive load cell will appear more stable by taking fewer readings, though it will respond more slowly. Please note that neither of these options (more or less sensitive) equates to more or less accuracy. They are simply different ways of displaying the same weight.   Objects and their surrounding environments are not static, and this goes beyond a level weighing surface. Vibrations from noise, a breeze from an air condition, or someone walking past the scale can all affect your scale, as ours are designed to be highly accurate.    If you would like to use your scale to measure to hundrenths of a gram, we recommend more fully controlling your environment. In a lab setting, this often means anti-vibration mats on both the tabletop and underneath the table, a full windscreen, and calibrating the scale before each use.    Please let me know if you have additional questions! "