On desktop you should be able to drag the dividing line between tags and groups to fit your preference.
On small screen devices, I don’t think that works. Additionally, such adjustments might be difficult to manipulate with a touch screen so probably we’ll need to think of a different approach.
Perhaps if we made the dividing line between tags and groups flexible based upon the number of visible groups. That way people who use tags to organise can minimise the groups to see as many tags as possible and those that use groups for organising can have maybe just 3 tags visible while the group section is maximised. I don’t think the collapsible groups feature is at all discoverable though so I’ll have to give some careful thought to that before building new behaviour that depends upon it. Would be annoying to have groups move up and down when expanded or collapsed too.
A top-level collapsible “Tags” item is probably the simplest approach to take but it does require more space on the left margin for every tag which is a downside for anyone using tags more than groups.
Hopefully that desktop tip helps for at least some of the time while we think of how to improve the small-screen experience.
Thanks for the feedback and suggestion.