If I look at the [data here on MSE](https://meta.stackexchange.com/tools) (10K only), I see that since the start of 2021 17 questions have been migrated away from MSE. That would boil down to no more then 80 questions a year. 

Since march 25'th over 45 questions have been deleted. That is more then 10 per day, or over 3,5K per year, or 45x times more often then a migration.

So yeah, Migration is an exceptional circumstance.