Yep, and there’s a thread (not too long) specifically about humidity packs, too.
From my brief experience, they seem to work pretty well for bringing humidity back up if needed, don’t seem to have a detrimental impact on potency, but they seem to have some impact on smell (and maybe flavor).
I don’t think I’ll use them going forward, unless I accidentally dry out some buds way too much before jarring – but even then, I’d be inclined to remove them from the jars once the curing process slows down.