If companies that still used plastic spools are starting to switch to cardboard, I think that's a good thing. Not only is it easier to recycle, but probably also lighter (your typical 1kg filament spool weighs around 200-300g), so the bulk should save some fuel for transportation.
Though I personally prefer using no spool at all (during shipping) 😉 Wherever possible I buy Masterspool refills.
Uh, that would be deceiving marketing, a 1kg spool should contain 1kg of filament...
But hey, maybe my view on this is a bit warped because I only buy filament from reputable brands (and usually from their own store) and not from marketplaces like "big A" where hundreds of sellers battle to be the cheapest.
It's a trend, away from the plastic spools which were decidedly made from a non-recyclable plastic.
It's always been curious to me that recyclable plastic was never even considered to be an option.
That said - cardboard is recyclable and biodegradable, so it's good no matter how you dispose of it.
But - it does have environmental downsides. If not carefully sourced, the wood can come from places where deforestation is a problem. It's also rather energy intensive to make, so depending on the energy source can contribute to CO2 emissions.
Nothing will be perfect, but cardboard is likely better than the alternatives.
I have had cardboard spools for a while. I am on the fence. They are much easier to recycle (no matter how many 1million and 1 uses for plastic spools exist). however they creak horribly on my spool holder, and are much larger than most of the similar weight poly spools i have, so i had to create bespoke spool holders for all 3 printers i have!
They don't seem to work very well with the AMS system from Bambu. Good news is can occasionally transplant them to a reusable (and printable too) spool.