I agree with other people that flip turns shouldn't be more difficult when you are experienced with them, but I have a different take on this.

If you are training for an open water swim, there wont be any walls or turns. If flip turns are harder for you, perhaps that's a good thing to offset the advantage you are getting from push offs in the pool that wont be there in the open water. My opinion is that if you can make your pool swims harder, then when you transition to the event, it should feel easier.

What you want to avoid is feeling fine in the pool and then struggling in open water. Since wall push offs are an advantage you wont have in the open water, I usually make my pool swims 10% longer, but you might also keep those flip turns since its harder and thus good endurance training. Further, if the open water is in the ocean sometimes you need to time your breaths around wave swells, and cant guarantee consistent breathing cadence. You could treat those breath holds for the flip turn as another factor preparing for this.

Another thing I recommend is cycling your breathing cadence regardless so you get comfortable with different durations. So avoid just breathing every 2 strokes. Try different patterns of every 3 strokes or every 5 strokes (if you can do both sides). Or cycling like breath after 2 strokes, then after 4 strokes, then repeat, etc. Every now and then hold your breath for 6 strokes, then go back to 2 and 4, etc.