Slow Notability sync on iPad mini and iPhone 16 compared to iPad 2nd gen

Hi

I am using Notability since 2017 and have more than 2100 folders.

notability using is following devises

iPad 2nd Generation

iPad 3rd Generation

iPad Mini 6th Generation

iPad Mobile 16 Pro

mostly i use iPad 3rd Generation for Notability, but from last few months ( approx 3/4 ) months i am facing late SYNC issue in IPad Mini and iPhone 16, when ever I take noted in iPad 3rd Generation its updated same time in iPad 2nd Generation and not in iPad Mini and iPhone

if I write notes in 4/5 different folders its updated in iPad 2nd Generation and not in iPad mini and iPhone 16, most of the time i have to open folder and wait for 15/30 sec to get it update

I don’t know why its taking so long whereas there is no such problem in iPad 2nd Generation

all my devises are updated

i have 2TB of iCloud storage and more then 60% is still empty

need advise how i can resolve above issue

regards

[Re-Titled by Moderator]

Original Title: notability sync