System data took up 21GB out of 128GB

I have an iPhone 12 Pro, and realise my storage keep getting smaller no matter how much files I deleted. And I realise other/system data is keep generating until it took almost 20% of my total storage. The storage continues to grow and until it max out my storage now I couldn't even turn the phone on.

I tried to search for solutions and it seems there is no better answer to reset the phone where I have a lot files/photos yet to back up.

Is this a strategy for Apple to push ppl buy larger storage phone and boost their cloud services. Because this issue seems to be there for a while and is only getting worse.

Such a huge disappointment for me as almost all my products all Apple and I am loosing my trust.