Published app size increased drastically

Hello there,

so I published my first app on the Play Store. All the assets I used in the app don't exceed 25MB, which is also the download size at the Play Store. After installing the app it needs a storage space of approx. 60MB. I wondered why the size more than doubled after installing it, but it's something still acceptable for me.
However, after a while, I got notifications that my device's storage is almost full and I wanted to delete some apps when I noticed that my app suddenly needs 200MB!? of the storage. From the user's standpoint, this supposedly small app would be one of the first to be uninstalled when in need of storage space, especially when the size is increasing limitless.
I tried to figure out why this is happening and after some research, I found out that Unity Ads is the culprit.
I deleted the cache and the app size went back to 60MB. Then I started my app and checked the size again after seeing the first ad. Suddenly it increased by 22MB to 82MB. After a few more ads it was at about 134MB.

Is it really necessary for Unity Ads to use so much storage space and to easily triple the app size?
In my opinion, that's a critical issue that shouldn't happen.

So my question, is there a way to prevent Unity Ads from filling the storage endlessly and if yes, how do I do that?

Thank you a lot in advance!