First thing to try, after removing the bits which are not compressed backup files, is to reduce the max backups to 2.
I think in any case it’s best to have some way to fetch these backups to somewhere else - your home for example. If you had a problem with your hoster and they deleted your account, you’d presently be left with nothing. Similarly if your account was compromised, and perhaps also if they had a fire.
Once you have some way - perhaps manual, perhaps automatic - to get offsite copies, you will be very close to having a way to check for and delete fragments.
I’ve suggested before that the dashboard should warn if the backup files have not been read for several days since their creation. That’s a relatively easy check, and in my view a good proxy for checking there’s an offsite copy.
You can also choose to put your backups into block storage, and you could do that using a different provider. Then you’d be less likely to lose both your installation and your backups.
I think there’s long-pending work to do which would not need to have both the backup and briefly the compressed backup file, but it’s not worth waiting for that. In the meantime, you need space for the N backups you are retaining, plus 1 for the backup being made in uncompressed form, plus 1 for the compressed backup which you need briefly before the oldest of the N is deleted.
You need disk space for N+2 backups, and if a backup fails you need to delete the bits.