All my Meta apps became "unknown sources" and Quest Link said "my pairing code had expired"?

TLDR: I fixed this by simply restarting my Quest 3 and also closing and restarting the Link app on my PC, but why did this weird glitch even happen?

So I have a Quest 3 about 3 months old, using v78.1030 (aka v78.1027). Today, I happened to look in the library app and noticed that all my apps seemed to have disappeared. Then I saw that the "unknown sources" icon had appeared in the left panel and when I clicked on it, all the Meta apps (all my games and even the Quest's operating system apps) were all being listed as "unknown sources" (see screenshots). Weird. My headset still seemed to be fully working. Luckily, I had previously allowed apps from unknown sources in the settings, otherwise, who known what chaos would have ensued!

I then took off my headset and restarted it, and noticed that the Meta Quest Link app on my PC had just popped up a message "your link pairing code has expired". So I closed the link app and restarted it. The link app then showed "headset not connected". When I put my Quest 3 back on, all was back to normal - all the Meta apps were no longer "unknown sources" and Link connected with no need to re-pair it. Hmm, OK I guess?

I Googled this issue and couldn't find anything at all. Any Ideas what may have caused this? Why would Meta's apps not be recognised as... Meta's apps 🤪? Do Link pairing codes even expire on a headset that is already paired? Weird.