In my first experience following a structured endurance-focused training plan, my anaerobic threshold (AnT) heart rate increased by 20bpm over a 3-month period. My aerobic threshold (Aet) heart rate at the end of that training block was equal to my AnT heart rate at the beginning. My years of intermittent running & powerlifting did not translate into a high AeT.
It sounds like you’ve been methodical about dialing in your AeT. You could consider getting a second opinion via a lactate test (I believe many people on this forum have gone to the lab at CU Boulder). Or base your training on these results, and spend a few months training below 110bpm, and re-test.
The age-based heart rate ratios apply to populations but with huge individual variance – best to ignore those.