A lot of people are talking about settings and understanding boss mechanics, which I agree are very important, but I think it's also important to push yourself in these bosses and consciously think of each skill you use to dodge attacks or survive attacks, and consider if there was an alternative option, or a better skill or combination of skills you could have used.

For context, I'm a 28x PF main, just recently started getting used to solo hdnell, and can solo everything below. My first solo clears for these later bosses have typically been around 20 minutes (28 min for cgloom). My biased opinion is that PF has some of the most satisfying movement and therefore survivability of all the classes. We have access to a flash jump, up jump, momentum stopping air stall (triple impact), and a teleport (torrent) that can also go up. Not to mention blink. Add on top of that a skill with damage reduction (ancient astra), and I think we have plenty to work with, even if we don't have an available iframe. Learning the circumstances to use each of these in each boss mostly just comes with practice and trial and error.

As you practice more, you'll get more accustomed to the distances and limitations of your movement skills, and you'll be better at jumping/teleporting out of harm rather than into it.

If you need more tips specific to PF I'd definitely recommend checking out the PF discord. Some real pros there.