In the last community update they spoke about "spending points", which is not something you do when you level up in 5e.
Each level, you'll have the option to choose a different class to spend points on and begin building a bespoke Multiclass character.
On top of that we saw the screen of a multiclassed character that don't specify the level of the second class. I guess it should be "LV 9 Druid / Lv X Sorcerer" if multiclass is implemented normally.
[img]
https://i.imgur.io/CWzksVw_d.webp?maxwidth=640&shape=thumb&fidelity=medium[/img] (how does this tag work?)
My completely made up theory is that they overhauled multiclas and when you level up you choose what features, not classes, advance. If you are a Rogue / Cleric you can keep keep acquiring rogue features but gain Cleric spells instead of sneak dice, for example. At least, it's the only think I can think of given the informations above, but I have all the doubts in the world about this because assigning a value to every feature and implement a point buy on top of that seems overcomplicated if not a nightmare.