Problems with backups saved in WebDav storage

[CodeShakingSheep]

I cannot use any backups created on my WebDav storage. I have issues in the following scenarios:

Download Backups
The backups cannot be downloaded. When I click the download button, WP displays this:

I turned on WP debugging and this is the log entry:

[07-Jun-2024 16:04:46 UTC] PHP Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 94384128 bytes) in /var/www/wordpress__4/wp-content/plugins/xcloner-backup-and-restore/vendor/sabre/http/lib/Client.php on l>

So, I increased my PHP memory limit from 256 MB to 512 MB. Still, not enough memory.

[07-Jun-2024 16:08:24 UTC] PHP Fatal error: Allowed memory size of 536870912 bytes exhausted (tried to allocate 484446208 bytes) in /var/www/wordpress__4/wp-content/plugins/xcloner-backup-and-restore/vendor/sabre/http/lib/Client.php on >

Then, I increased my PHP memory limit from 512 MB to 1024 MB. Still, not enough memory.

[07-Jun-2024 16:10:45 UTC] PHP Fatal error: Allowed memory size of 1073741824 bytes exhausted (tried to allocate 769667072 bytes) in /var/www/wordpress__4/wp-content/plugins/xcloner-backup-and-restore/vendor/sabre/http/lib/Client.php on>

I think, it's not feasible to increase the memory even more. FYI: The backup I tried to download has 788MB.

Transfer a copy of the remote backup to local storage
It's the same issue as when downloading backups, the memory limit is exhausted.
[07-Jun-2024 16:11:01 UTC] PHP Fatal error: Allowed memory size of 1073741824 bytes exhausted (tried to allocate 668995584 bytes) in /var/www/wordpress__4/wp-content/plugins/xcloner-backup-and-restore/vendor/sabre/http/lib/Client.php on>

Restore site
The worst thing is that I cannot restore the site as the dropdown to "select a remote backup archive to restore" is empty.

I'm in the situation where I urgently need to restore a site. What can I do now? Is there a workaround that I can manually upload a backup to the server and then restore it? Thanks for help @Ars92