Thanks for the perspective.

Wood is pine, and thats pretty much the way it looks when its stained. i happen to love the look of stained pine, some people dont.

Shouldn’t have stained it at all. Much too risky. Especially overhead. It ambers to a great color on its own.

I was told that it needed to be sealed and that sealing it would change the color significantly from its natural appearance. I was advised to stain to ensure color consistency.

Your wood has multiple “milling marks” and what looks to be live edges on the beams. If you wanted it more uniformed you would have needed to sand and grain sealed before staining. This would have been many man hours of work = $$$$. A simple water based poly sealant would have been best.

Are you sure it's the stain? Or, is it that for whatever reason, the wood is not the same in the other rooms?

It's pine. Pine takes up stain unevenly. You can minimize this, but not eliminate it, with a sanding sealer.

Was this material added after the fire, or did it survive and need to be refinished? Because heat and smoke can also alter wood.

IMO staining it was the mistake and pine for sure is hard to work with .

After sanding, the pine should have been sealed before staining. Here is a good article to address all your issues:

https://www.hunker.com/13413226/how-to-stain-knotty-pine

Thanks all. The wood is the same in all rooms and the stain has been taken up very differently on different sections of a single board. The wood survived the fire and the areas that have taken up the stain the worst are those that were most directly impacted by the heat. Consensus here seems to be that we shouldn't have stained it -- presumably if we want a consistent outcome we will need to re-sand or strip and start from scratch.

I‘m a little late to the game,but maybe this will help someone else. you can solve this blotchiness with a stain sealer (sanding sealer, de waxed shellac, etc....) cut with mineral spirits up to 50/50 will solve this problem. you can test with a thin coat of 100% sealer, a 75:25 sealer to Mineral Spirits ratio then a 50:50 Ratio to see which works best. A pre-stain conditioner might help, but doesn't always work as well.. Some types of wood - notably pine, maple, birch and cherry, do not like to take stain evenly so by partially sealing your wood first you will get better results.

^ then a glaze, not a stain, if you want consistency.