Their official explanation, that bitcoin txns are getting stuck due to low fees, is plausible.

See: https://mempool.space/graphs/mempool#24h & zoom out farther to see how the current fee regime is higher than usual.

This does show a nasty form of contagion within crypto. One player pauses withdrawals which causes a run for the doors elsewhere, any given L1 can only process so many txns per second, so fees spike, their code doesn't handle it gracefully so more players pause withdrawals to fix it.