macOS/linux have a few system wide shortcuts that Joplin used to respect such as:
ctrl-E # move cursor to end of line
ctrl-A # move cursor to beginning of line
However since about the time of the WYSIWYG editor implementation, those system wide shortcuts seem to have stopped working.
macOS 10.15.7 Catalina
Joplin 1.3.18 (prod, darwin)
Revision: 6b75485 (master)
These are now mapped to Cmd-Left and Cmd-Right for moving to the beginning of the line and end of line respectively. The change probably happened when Joplin switched to a new editor component (and thus a new set of default keybindings).
Although I find that a bit odd maybe because ctrl-E has been bound to open external editor for a long time, and I know on my linux system ctrl-A has always been select all.
Hopefully you find the new keybindings useful, we do plan to eventually allow remapping of editor keys so you might need to hold out for that.