*In hot sunny days before the virus all of the shops were open, pubs were open, there were museums, aquariums, softplays, attractions, hotels/B&Bs/holiday parks, cafes, restaurants, etc. So all the mass groups of people were more spread out, there were extra toilets available in cafes/pubs, venues had extra staff taken on to cover the additional work during the peak season and the peak would ebb and flow based on weekends, bank holidays, school holidays.
Yesterday (and throughout lockdown) there was a mass of people concentrated into one specific area - the beach - as there were no pubs, cafes, other attractions, etc to siphon any of them off elsewhere and spread out the concentration of visitors. No extra toilets as no venues open so only the public toilets available which are enough on their own to cope with that amount of people.*
This. I can't think of any other reason why it's been so busy round the lakes in the Lake District recently - especially with visitors who don't normally go to the Lakes. A lot of them wouldn't have been here at all and others would have been in cafes/at visitor attractions etc.