They more-or-less improved the keyboard immediately after the SP3. The SP4 is a night-and-day difference to the SP3 (to the point where I was considering getting a SP4 keyboard for my SP3 when I still had it), and they've gotten better since.
I have the non-cover version of this (or at least, it's another Logitech keyboard with a very similar design but lacks a cover - the K380s), and I also have a Keychron B1 Pro and a TKL mechanical keyboard, but my cheapo K380s still feels better to use to me.
Unless they have a way to lock open, foldable keyboards will always subtly bend which is annoying enough for me to ditch the folding part entirely.