While it may be that the uptick is caused by the lockdown straining relationships, it may also be a case that the lockdown artificially depressed demand and then easing of the lockdown enabled people, who would have otherwise filed earlier, to all file at the same time

It's easy to slide along in an awful relationship as the water slowly gets hotter and hotter, hoping that your spouse will somehow come to their senses rather than boiling you alive. A sudden shock that makes you realize you're long overdue to get out can be a very good thing. (Highly recommended.)