app uses too much storage and drives phone crazy (and perhaps even the check/warning may fail?)

[DJCrashdummy]

Description

perhaps it is a "chicken or the egg" problem, but it happened 2 or 3 times the last year, so i took the time to open a bug report.
my device is low on free storage (around 500 MB to 1 GB) and yesterday i noticed once again it was going against 0. - yes i know a bunch of apps use quite some storage in the background but i always notice when my storage was going really to 0 this app was always also going bonkers.
with that i want to describe, that mostly all the former free storage of 0,5 to even >1 GB is used by this app! and not the cache gets that big, but the app data! so the only possibility to get the whole phone somehow working normally again, is to delete the app data. 😒 ...which is surely not the best idea. hopefully not all keys/ids from the exposure framework get deleted as well?

Reproduction steps

1. install the app on a device with few free storage
2. wait some time resp. normally use your phone
3. after days, weeks or even months notice some apps crashing or misbehaving, because the free storage is really at 0.
4. have a look at the app details of this app and see all the formerly free storage (i guess the highest value i noticed was around 1,3 GB) occupied by the app data! 🤨

Additional helpful information:

• Version of the app: 2.1.4.1247-QA_266

What did you expect

this app should not use ridiculous loads of storage! perhaps around 100 MB is ok... but more is not applicable for some low end devices. - people use their smart phones mainly for other things than just corona tracking.
i guess it is somehow related to #286, but i have installed the german app in parallel (on the same device), which also downloads an insanely amount of data (even more), but it does not have this problems with using that crazy much app storage from time to time.

additional observation

BTW "using the german app in parallel":
as already mentioned i also have the german app installed (on the same device) - the one which is completely FOSS (https://f-droid.org/packages/de.corona.tracing/) - and little more than 2 weeks ago it warned me about some "higher risk" for the first time... but the stopp corona app stayed silent as it has always been since i've installed it. 😕

1. how can this happen?!? - no, i was not in germany during the last weeks! and no, the last time i had to clear the app data was months ago!
2. please don't tell me that the stopp corona app needs GBs of free storage to check the keys/ids and if it doesn't get that much storage, it fails silently!?!