@PaPaSmokes
Too Long, Didn't Read (TLDR):
Your smoked sausage looks totally fine.
I feel like you have a false expectation of what a smoked sausage looks like, making you less happy with end product than you should be! A few things you said lead me to conclude your expectations may be off. Those SMOKED SAUSAGES look fine!
Here is what you're saying that makes me think you're possibly confused on expected results.
1. You keep saying BRATS. THESE ARE NOT BRATS!! Bratwurst is a FRESH UNCOOKED sausage, that is then FAST COOKED. In Germany, it is usually cooked in 170f water by poaching. You can then put brown marks on it in a pan or grill.
--Alternative cooking is just raw then straight to a pan, or grill, cooked high like 300f and up, done in 20 minutes. However, this does not produce as good results as poaching (or sous vide) first, as the high heat on raw un-denatured proteins will cause fat to melt out, lising juiciness. Also the casings tend to pop due to steam produced before meat is denatured i.e. cooked.
2. SMOKED sausages, cooked at 130 to 180f external smoker temps usually, look just like yours. They only achieve color from smoke, they do not exhibit the browning from Maillard reaction, very much. Maillard takes place at 250f and above really. If you are looking to get a smoked sausage that looks like a BRATWURST OFF GRILL OR PAN, then you will be dissappointed.
3. Maybe you got led to this expectation by false claims and incorrect use of terminology on some popular YouTube channels... I watch Chudds and Smokin Joes Pit BBQ, and I don't think I have ever seen a video where they use correct terminology! They constantly say they are "cold smoking" stuff when really it is 150 to 170f, not below 75f that Cold Smoking refers to. Both those guys, and tons more, are BBQ guys, cooking on grills at 225 and up, not smoking! All the nice reddish brown sausages they show are fast cooked usually in a 225f and hotter grill.
4. The recipe and seasoning you used, BB Mango Tango BRATURST seasoning... isn't for a smoked sausage, it is for a bratwurst. Being confused about what a bratwurst is and how it is cooked, led you to think there might be Cure1 in the mix, I think. It has mango, jalapeno, and maple sugar, that's about it!! Barely any salt, though some is listed in their maple sugar flavoring pack...but no nutritional labeling, so you can't determine how much. I would never use a product like that, where the salt content is a complete guess. If you can't ensure 1.5 to 1.7% salt, normal saltiness for sausage, I'd add my own.
--Why do I care about salt? Salt is the #1 thing that locks up water, lowers Aw, and inhibits bacterial growth while you are heating up meat through the danger zone! With little or no salt, bacteria are much faster to grow. Since the crux of your concern here is "Did my sausage get to lethality temps fast enough to keep bacteria or botulism from growing?", I am adding this note on salt so you know how it helps, for future cooks.
Ok, I need to go get another Mai Tai, hope that helps!