I heard they patched this already? But can someone explain to me how this happens? I'm so scared of having this glitch! I ordered amiibos the other day and I'm in the process of replacing my existing villagers with them. If anyone could enlighten me on this, I'd very much appreciate it!
No I don’t think it’s patched, it happened 1 or two days ago with Raddle’s house. Basically if you have a villager that is moving in, and you time travel backwards, it keeps the house of the villager you moved out.
I did a quick check on the ACNH Discord server, and there's reports that the bug has been fixed, but previously bugged houses will remain with their incorrect exterior. But I didn't delve too deep into those reports.
So while you should be fine, it's easy enough to avoid the bug anyway. The bug is caused by skipping the "plot sold" day after the camper forces out a villager, either by TTing multiple days forward at once, TTing backwards any amount of time, or even not TTing but just not playing the game on the plot sold day.
If you TT, make sure you TT one day at a time as you're moving in a villager and don't skip days. I'd recommend taking a picture of the empty plot just for assurance. If you aren't TTing, make sure that you at least load the save file once on the plot sold day even if you don't do anything else that day. As long as you do those things, you won't encounter the bug.