iOS system takes up every freed bit of disk space

I have spend weeks/months now deleting apps to get enough space to simply use Whatsapp or Signal.

I keep on getting the message: not enough disk space available to open whatsapp or signal.

I have deleted almost every app I had on my iPhone now, and still it's not enough. Every time I created free space after a small amount of time, System has taken up the free space created.

Why is that and how can I stop it?

for example, a fortnight ago, this was my disk space usage:

Just half an hour ago, I check again, and now it is already this:

it doesn't stop and it annoys me a lot.

I do not know if it is a coincidence but it started happening around the time iOS26 came available for download. Is this a sneaky tactic by Apple forcing people to upgrade to newer iPhone models?

Or what could be the reason and what is the solution to stop this?