You will undoubtedly miss the strict threading because you are coming from Zulip. My main recommendation is to make the most of Discord's "Forum" channels. They are ideal for organizing feature discussions and bug reports without packing the main chat.
The only significant drawback we discovered is that Discord doesn't come with organized work tools because it was designed for communities. You can use paid cross-platform tools like DailyBot for standups and agile work, but they can sometimes feel a little heavy and Slack-first. We just wanted something simple that used Discord's built-in UI, so I made a custom bot for us called AsyncFlow (https://www.asyncflow.space) to handle our async standups and team polls for free.
Happy to answer any questions if you end up making the switch!
If you like the communication flow of Discord, Fluxer is also worth keeping on your radar. I would never trust my essential comms with Discord personally, and Fluxer is looking to be a great option.