Eh...
The set of people who can maliciously modify it is the people who run f-droid, instead of the cloud provider and the people who run f-droid.
It'd be nice if we didn't have to trust the people who run f-droid, but given we do I see an argument that it's better for them to run the hardware so we only have to trust them and not someone else as well.
The cloud isn't the only other option, they could still own and run their own hardware but do it in a proper colocation datacenter.
You actually do not have to trust the people who run f-droid for those apps whose maintainers enroll in reproducible builds and multi-party signing, which only f-droid supports unlike any alternatives.