I'm not a paying customer (yet) so don't feel any obligation to do something like this... I'm not sure if your customers actually need something like this - although I'd find it useful myself.
Currently, for backup retention, there is a dropdown of different types of retention schedules. These retention schedules are quite varied, and the ones towards the bottom are more geared towards the rsync backup option, I believe.
I like the options further down in the list (like 2 daily, 4 weekly) because they provide options if someone messes something up and you don't notice it for a while. However, currently I've been sticking with the tarball option because it's just a lot faster for backing up things like NextCloud. The downside though, is that tarballs are a lot larger, and running a 2 daily 4 weekly tarball backup uses up a lot of space.
I was wondering if it was at all possible for Cloudron to offer a few more retention policy options... things like '2 daily 2 weekly' (although I'm not necessarily sure this is the particular one you guys want). Whether that's by adding more options in the dropdown, or allowing us to set a specific number of daily, weekly, and monthly backups retained - I think either would be pretty awesome.
In any case, let me know what you think, and thank you for all of the work that you do. Your software is really helpful.