I’ve made other changes also - to the TR training plans. In particular - the Low Volume sweet spot base plans have intervals that are too short and too high an intensity for my liking. I’ve replaced a lot of the threshold intervals with with longer intervals in the 85-90% range.
I still do VO2max workouts, but have replaced the likes of Spencer and Kaiser with hard start intervals.
These changes have made things much more sustainable for me.
Start with reducing your FTP, and stick to the TR plans. See if that helps first.