A similar frustration / reason for getting it wrong sometimes: in slack, the behaviour of shift+enter entirely reverses if you're inside a multi-line code block. If you normally have enter to send and shift+enter to line break, then it'll do the opposite while inside a code block.

This is useful if you're trying to type verbatim inside a block, it's less so if you have a strong muscle-memory to shift+enter and do so while in the code block and find yourself sending half a message.

I also use a mixture of teams, discord and slack, and while slack does allow for customisations, I'd always rather get used to defaults to avoid having to configure on every machine I use.

There isn't quite a consistent well agreed default for the behaviour across applications, and that too is a source of frustration.

So I've taken to typing up any long messages in a PM to myself, and then copying that out to my intended target once I'm ready.