Earlier quoted context omitted.
Who is "you"? I have the training and sometimes go significantly deeper. I use a competing Garmin smartwatch, works great. Do you understand why?
How deep are you going? What gas mixtures are you using? Which Garmin are you using? If you're using a Mk3i or a G2 (or related) you are using a diving computer in a smart watch form factor. It is custom built for this... unlike the Apple Watch Ultra.
We use a variety standard breathing gas mixes for the depth range based on limits imposed by density, narcosis, decompression time, and oxygen exposure.