Debian package fails to install on testing (bullseye) (nonexisting dependency)

libappindicator3-1 package does not exist in Debian testing (and probably won’t in the upcoming stable release). The package is subject to be removed from Debian.

Proposed solution by Debian: migrate to libayatana-appindicator.

Delta Chat version

deltachat-desktop_1.14.1_amd64.deb

Expected behavior

debian package to be installed after

dpkg -i deltachat-desktop_1.14.1_amd64.deb
apt install -f 

Actual behavior

Selecting previously unselected package deltachat-desktop.
(Reading database ... 337287 files and directories currently installed.)
Preparing to unpack deltachat-desktop_1.14.1_amd64.deb ...
Unpacking deltachat-desktop (1.14.1) ...
sudo apt insdpkg: dependency problems prevent configuration of deltachat-desktop:
 deltachat-desktop depends on libappindicator3-1; however:
  Package libappindicator3-1 is not installed.

dpkg: error processing package deltachat-desktop (--install):
 dependency problems - leaving unconfigured
Processing triggers for hicolor-icon-theme (0.17-2) ...
Processing triggers for mailcap (3.68) ...
Errors were encountered while processing:
 deltachat-desktop

sudo apt install -f
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Correcting dependencies... Done
The following packages will be REMOVED:
  deltachat-desktop
0 upgraded, 0 newly installed, 1 to remove and 0 not upgraded.
1 not fully installed or removed.
After this operation, 289 MB disk space will be freed.
Do you want to continue? [Y/n]

Steps to reproduce the problem

Set up a Debian testing machine and run:

dpkg -i deltachat-desktop_1.14.1_amd64.deb
apt install -f 

Thank you, this is important. I opened an issue over at https://github.com/deltachat/deltachat-desktop/issues/2040