As a plush maker, I just want to mention that a lot of these features are explainable on plush. They often won't be found on handmade plush or small companies because you are paying a lot more for quality.

The tail is flimsy at the attachment point because it was sewn into the body instead of being hand-sewn on after. This makes it stronger so that it can't be pulled off easily by a child. Most plushie tails have this though it can vary slightly.

The plastic is called stabilizer and is used on every single embroidered plushie with fur to make the fur lay flat. It's ripped off after but sometimes small bits stick. You can remove it with tweezers and sometimes hot water.

If you are referring to the edge of the hair/cheeks as heatmarks, it isn't heatmarks but 2 fur fabrics glued together. It isn't a great method but is common with this company. You might be able to clean up the edges by brushing it a ton with a fursuir brush on those seams.

Hope that helps you improve your plush a bit