I have had 30 or 40 bubble tip anemones over the past 10 years or so and not one of them have ever had bubbles. What am I doing wrong they are huge and healthy but just know bubbles
I have found that they stretch their tentacles for three reasons:
They are stretching for food,
They are stretching for light,
They are adapting to high flow.
Try feeding them frozen brine shrimp for a couple of weeks (2 - 3 times/week). If that doesn't work, reduce flow if it is high. Then try giving them more light, but gradually.
But there may be some "morphs" that simply don't get bubbles.