PNWSierra

I have had driveability issues (hesitation,, gear hunting,, RPM flares, reduced power at low speeds) since approximately 20k miles on my 2018 Sierra 1500, 5.3 with 6l80. 33k miles now. It finally got bad enough that I had to take it in to dealer. Before taking in I checked ATF levels and noticed a decent amount of what I believe is clutch material. The dealer was not able to duplicate my concerns but did drop the pan and fill with fresh ATF and claimed the amount of clutch material is normal. My driveability issues remain so I checked the fluid again today. While the ATF is noticeably fresher, there is an even greater amount of black deposit in the fluid. Can anybody confirm this is "normal" or is it likely related to my driveability issues? Before dealer work (pink fluid) and after (red fluid) attached.

I have a 2018 Sierra 1500, 5.3, 4wd, with 6l80, 26k miles. I have recently been dealing with stumbling and hesitations under light acceleration at lower speeds, it feels similar to a misfire. It is not noticeable under heavy acceleration. I do not tow much, maybe 600 of my 26k miles have been towing. No check engine light. I had identical issues with my 2015 Sierra 1500, 5.3 with 6l80. I had these issues until the torque converter took out my transmission at 33k miles. I took it to three different dealers and each one fed me an excuse of adaptive learning transmission or we can't recreate the issue. The transmission finally went the next day after taking to the last dealer. That transmission was replaced under warranty and all issues were resolved under they all started to come back at 46k miles. I traded it in at that point for my 2018. I am certain the dealership will be of no help to me now without a check engine light. My question is, is it too late to save my current transmission now that issues have started to come up? Would an upgraded torque converter save it or has the damage likely been done by fragments/contamination? My nearest dealer is 60 miles away and it is very frustrating to burn a day, explain problems, and have them reflash the transmission or tell me that they can't recreate the issue. I feel like I'm driving a ticking time bomb.