The default key for "Add key to SSH agent" is Cmd + H on MacOS. This is a bad choice since this is the default global key for hiding the currently active window and the command does not get executed.

Maybe you could consider Ctrl + H similar to Linux?
If that was the case "Remove key from SSH agent" should be changed to Ctrl + Shift + H too probably.

KeePassXC - Version 2.6.1
Revision: 9a35bba

Qt 5.15.0
Debugging mode is disabled.

Operating system: macOS 10.15
CPU architecture: x86_64
Kernel: darwin 19.6.0

Enabled extensions:

• Auto-Type
• Browser Integration
• SSH Agent
• KeeShare (signed and unsigned sharing)
• YubiKey
• TouchID

Cryptographic libraries:
libgcrypt 1.8.5

Operating System: macOS