Step 1 is to not be vague. Tension exists first where people prevaricate, before ever graduating to disagreements. Leaving things unspoken encourages the mind to fill in the gaps.
I’ve done a lot of conflict resolution work (mainly in the context of political organizing and de-escalation), and a critical part of that has been helping the conflicting parties recognize and reckon with the root of their conflict. Many such conflicts reduce to either a misunderstanding or a perception of a power imbalance, both of which usually end up being unspoken and difficult to identify once people are heavily invested in “the argument” instead of in resolution.
The most important element really is encouraging the participants to be entirely honest about the source of their feelings of strife, and to give and receive feedback clearly and with actionable steps to resolution. Haskellers are broadly pretty good at this, though there have been notable community-level arguments that got pretty toxic (cabal/stack and codes of conduct being the main ones that stick out in my memory). I think the Haskell community is largely good at avoiding this because the community is not “all of a kind” in terms of why they write or think about Haskell, so there is a necessity to be a “good citizen” in your dealings rather than leveraging a community or corporate position to get one’s way. (This is not to say these dynamics are not at play, at all, just that they are less pervasive than in other communities I’m a part of; Haskell maintains a pleasantly anarchic bent, at least to my mind)
Being clear can be uncomfortable, upsetting, etc., but is generally less stressful and harmful long-term than allowing vague problems to fester and morph into unmotivated hostility.
There are, of course, situations in which one or more participants just have views incompatible with such resolution, though these are usually rooted in matters which are not specific to Haskell and are related to the social constructs which we deal with as people in flux. Deconstructing and resolving these tensions is harder, but possible.