There’s a closed discussion from 2021 with this post, but I was curious if it could be reconsidered as a feature request. While zooming in and out is a workaround, everyone on my team would need to know to do that and remember to. The calendar view is most useful if it allows us to see at a glance the items (or at least number of items) due a certain day. The “+” icon suggestion made perfect sense to me and is what I’ve seen in other software. That would be intuitive enough for the whole team so they know when to zoom out.
From 2021:
"Hi Talia @TRB-monday.com, thanks for getting back to me. The zoom in and out trick works, but I think it really needs some improvement because in order to see more than 8 items / date the screen has to zoom so far out it is not funny 
Also there is no indication on if the box is showing all items or not so we will need to zoom 1 step more than needed to ensure all items are showing.
Perhaps there could be a (+) sign on the box where it is not showing all items? So at least we can be aware that there will be more items on that day. Hover on top to show all items could be handy too! "