For me, as a polyamorous person, the holidays are a peak time of awareness that nothing is black and white in relationships and nuance matters. External expectations on all partners in a network tend to be at a high - we all try to reach in and co-rely on one another - and while sometimes this works out gloriously well (I've got very cute pictures of my metas in hats I knit them a few years ago and some good thanksgiving photos of 2019 to attest to this, as well as some now-ancient-history memories of friend-holiday-weeks with massive interconnected network Festivus parties and New Years' nights filled with cuddle piles to lean on as proofs) it can also lead to some moments of "let's figure out everyone's minimums and make well enough work." And for some people, that latter can be very uncomfortable, or can feel counter to the spirit of how they practice their polyamory the rest of the year and like too much of a bow to family of origin who usually don't impact their lives; or like a sign of hierarchy they thought they were "past" that then shakes their internal security in relationships.
Nuance, in this case, means all the ways that the "new patterns" and the ways we try to set ourselves up for different, nonmonogamous norms don't hold up strictly in the way they'd be stated as an aphorism or a philosphy. The ways we can try to be non-hierarchical but nesting with people or coparenting (or anchoring our lives with people even if not nesting) impacts the realities of how much time we have to spend with whom or who our families are happy to have along to events if we aren't hosting. It's the details of "well we can bring additional people we live with or one partner each to this" that create artificial boundaries for people. It's the "jealousy moments" around this time of year that are not a failure of the relationship but are a function of "it's one busy month." Love is infinite but time isn't - and as much as parallel polyamory is fully workable and healthy, it also is something that takes time to be able to manage, because you have to do things twice or more with different sets of people.
But, walking through those moments where you have to process jealousy and whether or not you can actively live up to your philosophical intentions can be a really beautiful process of growth for relationships - you can better come to understand your own underlying needs by seeing what parts of these situations trigger you or which parts leave you calmer and better able to cope - and you as a relationship can understand better what parts of traditions and social obligations are more engrained for each of you and going to impact your interactions as you move forward (and how those change over time).
In unrelated news, there's Ready for Polyamory merch in the shop now! Tees, tanks, and more! If you're interested, it's here for you.