When meds affect your heart rate, the whole training metric gets thrown off. You have to figure out what actual effort feels like underneath the HR changes, otherwise you're just spinning your wheels.
Assume it's because of that ingredient but yesterday was super lightheaded around 11 until at least 3. Faded after. Not thirsty or hungry. Thought maybe migraine creeping back since gastric surgery. Passed so maybe. Heart rate flat on my watch that window.
Caffeine sensitivity shifts for a lot of people on GLP-1s. Pre-workouts that were manageable before can hit harder. Worth checking blended drinks for synthetic caffeine - di-caffeine malate and caffeine anhydrous are harder to estimate than coffee. If the rapid heart rate correlates with supplement timing, that is likely the explanation before blaming the peptide.
The heart rate spike with stimulant compounds is expected but the crash you're describing sounds significant. 100 units of each after one week at 50 is a fast escalation. Heart rate elevation plus hard crashes points toward the dose being too aggressive for where your tolerance is right now. Pulling back to 75 and holding there is worth trying before going higher.
Moving from MJ to reta with a pre-existing HR condition worth tracking carefully - reta's mechanism is different enough that some people who had HR issues on tirz find it more manageable, but the baseline monitoring protocol your GP has in place is the right approach either way.