Hello,
attachments are shown with a download arrow, and when I click on this, the attachment is downloaded to my android device and it is shown. Very good!
Now, to remove the attachment (for space issues on my small android deivce), how can I remove the downloaded attachment, so that the space is free`d up on my android device and the download arrow is shown again?
You may not like it, but there is a cumbersome workaround ... if you have only "so many" and not too many notes with attachments in total.
Remove the App from Android, reinstall it, only download the attachments you need.
I could also well imagine a function where I allocate Joplin for example 2 GB cache for attachments and then the oldest data is automatically deleted from the cache. Of course, that doesn't quite fit with the philosophy of an offline-first application. On the other hand, it can get really cramped on the phone if you use Joplin not only for text, but also for data storage.
By oldest data I mean the attachments that have not been used/opened for the longest time.
That doesn't help you now, but maybe forms a function for the future.
To my knowledge, deleting a pic from the main Joplin app results in it being deleted from the cache... sometimes later.
Up to now this I think is meant to be synced (so the pic ends being deleted everywhere).
Now, one could deepen the issue with some servers, like flavors of NextCloud that intentionally do not replicate Android deletions back to the computer synced folders (for instance the /e/OS cloud, Murena, behaves like this). But I think this probably is superseded by Joplin behavior...