It can happen due to various reasons, but the way laser printers work is they electrostatically charge a toner drum, the toner particles "jump" to the right spot, and are then deposited on the paper that has an opposite electric charge. Then the whole thing goes through fuser rollers that "bake" the toner into the paper. If the toner is low quality, the fusion step wasn't hot enough, or the paper and toner are incompatible, you might not get complete adherence of the toner to the paper. This can cause that flaking behavior in the future.

The trick is to do your research on the printer and toner to make sure they have a high quality finish.

For paper, a heavier than normal printer paper (like 40lb text paper instead of the normal 20 or 28 lb) that has some percentage of cotton in it can last for hundreds of years if you store it in an airtight container.

I have a TON of old HP LaserJet printouts from the 1980s and 1990s have have done this - if you have them stacked in a box, you find them stuck together and pulling them apart takes the print off with one or the other sheet.

I haven't experimented with work arounds but perhaps separating with wax paper or parchment might be helpful.

In the 1980s we used photocopies and sheet protectors to play a tabletop game (SFB), and over time toner would pry off the paper and stick to the plastic. Not sure if modern paper stock or printer fusers do better.

I would imagine that it would be related to regional environmental conditions such as humidity, temperature, air pressure, etc. though I'm no expert on the chemical properties of toner.

I also never had this happen, and conversely find that inkjet fades, and will be totally ruined if it ever becomes damp.