The damn project helps mappers by dividing some big area into smaller squares that a human can map.
The development happens on GitLab. Chat on Gitter.
The community discusses all the damn things. The community makes damn decisions.
The community encourages split to smaller groups with narrower specialization. It makes no sense to discuss JOSM client for mappers and a web client for managers in the same group. The community encourages creating new clients of all kinds.
Discuss. Try to be empathetic, respectful, patient. Try to discuss without emotions.
Distinguish if you are talking about what, why, or how.
How is discussed only after what is agreed.
If you present what, be prepared to explain why in different points of view tirelessly.
If you discuss what because you agree/disagree with it, try hard to understand why and provide constructive feedback.
Don't forget to stick with developers guides (i.e., branching model, keeping a changelog, etc.)
Because it is nice, and it increases effectivity.