Each note in Joplin is a separate Markdown file so there is only a real chance of conflict if two clients edit the same note at the same time. That is much more sync-friendly than an encrypted password database file.

I have yet to hit a conflict but it's just me editing notes and I don't usually use multiple things in the same note at once. I did have a problem getting syncthing to work well on my phone (a pixel with newer Android) where it worked OK on my tablet and other devices. I had to hardcode the address of my laptop in syncthing settings on my phone and then it seems to be happy that way.