It’s important to do both tests when you are well-rested and separately from each other (I’m not sure if you did them in a row or not.)
If you were tired during the warmup I think you might want to do the test again, especially if you think your anaerobic threshold might be higher.
If the difference is still less than 10% then yes, Z1 for your aerobic base work instead of Z2. And ME or some high intensity work depending on where you are in your training cycle and your goals.