I have neither found nor heard of any limit (real limit…Wyze will officially tell you the limit is 32GB). I personally use 128GB MicroSD cards in all my V2’s, V3’s and Pan Cam with no problems.
Having said that, you do have format the cards into actual FAT32 format for the V3’s to work (at least as of a couple of firmware tests ago). The V2’s have basically always worked fairly well in exFAT, though I’d recommend putting the cards to FAT32 for those as well.
I’ve read of people testing 256GB cards. I don’t personally know of anyone trying anything larger, so I can’t say if anyone has succeeded or failed with cards over 256GB, but in theory they should work fine if formated to FAT32. Keep in mind that Windows won’t natively allow you to format anything larger than 32GB cards into FAT32, so you have to get a different program to do it for you. I use this one:
Here’s a more elaborate and clear explanation on why Wyze says they’re limited to 32GB but why the Cams can in fact definitely use much larger cards than 32GB:
In short, it’s a difference of Capacity standard (SDHC and SDXC) vs file structure standard (FAT32 vs exFAT); and what their default standards and support are. You can make larger cards use the FAT32 file format (not their default exFAT) and then Wyze cams seem to work fine with them.