steps to reproduce..
use /locate to find a Trial Chamber
see the output text reading "The nearest Trial Chambers is at ..."
expect proper English, "The nearest Trial Chamber is at..."
or "The nearest Trial Chambers are at..."
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Comments 5

This may be intended and grammatically correct, since "Trial Chambers" is a proper noun. Compare a shopping mall name "The Shoppes..." or a spa named "The Baths..." We wouldn't say "The Baths are my favorite places." We would say, "The Baths is my favorite place."
Or compare "Ocean Ruins" and "Trail Ruins" in-game.
Since it's not The Trial Chambers I feel that's kind of a poor comparison because it's yet a different context and it also oversimplifies a nuanced aspect of grammar. But it may be so. How can we know for sure? Many instances of inconsistent pluralization have been corrected in the past.
BTW here is a list of some instances in videos, posts and articles where Mojang specifically uses Trial Chamber when referring to just one of the new structures specifically in a singular manner.
https://youtu.be/ONs7kTlqGw4?t=104
https://youtu.be/bBr8BBrk1v8?t=33
https://youtu.be/8jwAtfyxhlk?t=144
https://www.minecraft.net/en-us/article/trial-chambers-first-peek
https://www.minecraft.net/en-us/article/composing-trial-chambers
https://www.minecraft.net/en-us/article/introducing-mace-and-ominous-events
https://www.minecraft.net/en-us/article/trial-chamber-prepping
https://x.com/Minecraft/status/1798023306714771656
https://x.com/Minecraft/status/1798730986227896483
https://x.com/Mega_Spud/status/1727382848301412768
https://x.com/Mega_Spud/status/1801294572632338640
https://x.com/MinecraftES/status/1798033415251607730
https://x.com/CornerHardMC/status/1804245055915593792
https://x.com/minecraftjapan/status/1741353498518671366
Not to mention The Advancement "Minecraft: Trial(s) Edition" has the description: "Step foot in a Trial Chamber"