it means the network is maturing, people are starting to deploy capital more efficiently. Small chans dont route (much)

you can see the number of nodes and channels in the network falling yet the capacity still grows. Having tiny chans that don't do anything is a complete waste of resources from node operations point of view, closing them in low fee env and redeploying that capital to new chans or taking it back to cold storage it the way to go. Btc at risk is a btc that needs to be productive, otherwise you just lowered your stash safety with nothing in return, potentially just risking a bad force close with a shitty peer