I have noticed the same. Each team that has quit on their bowl game has not only blamed Covid, but also transfers and opt outs.
Covid is the easy out for these teams that have lame duck coaches and a mass exodus of starters. Would be nice to hold these schools accountable (Miami, Virginia, Hawaii, BC) but the root of the problem is too many bowl games. And before someone argues that too much football is never a bad thing does not understand quality over quantity.