Given that it’s been well reported they cut loan offers not long ago, I suspect this is almost certainly the case (and was possibly done at the same time but hasn’t been noticed until now).
The current situation has the potential to make situations finacially very tricky for people. Which means it could also make things financially tricky for banks.
As a neobank with a lower capitalisation than long established banks, and also not yet making a profit, it makes perfect sense that Monzo would want to reduce their exposure should there be a high percentage of customers unable to make their payments.