"Think" (thinkpad, thinkcentre, etc.) series have AFAIK completely different R&D team plus the whole aspect of building on top of what was done for earlier models, and on those the UEFI Capsule mechanism (which allows passing firmware updates from booted OS to firmware) works just fine - it's also used to ship firmware upgrade as part of Windows Update.
Lenovo's business/prosumer line is one of the best in terms of firmware that I've seen so far (though I do have my gripes with their decisions on laptops with Nvidia GPUs).
I don't even want to touch Lenovo devices that don't have "think" in their name, and even that has been tainted by their consumer brand at this point.
> Lenovo's business/prosumer line is one of the best in terms of firmware that I've seen so far
A few years ago Lenovo put out a buggy firmware update for the Thunderbolt controllers in a couple generations of Thinkpads (the list is here: https://pcsupport.lenovo.com/ca/en/solutions/ht508988 ) that caused excessive writes to the controller's EEPROM. This would eventually wear out the EEPROM, which would stop the controller from functioning. You would then have issues like USB-C devices not working, display over USB-C not working, and charging over USB-C not working. Lenovo released a firmware update to fix the issue, but everyone whose controller had already broken needed a motherboard replacement. If your device was out of warranty, Lenovo made you pay full price for the new motherboard even though it had broken because of their firmware update.
I am aware and my laptop was one of the devices that needed the patch.
And yet, I'm still of the opinion that Lenovo's firmware is up there. It's actively maintained and it fails less often than the firmware I've experienced from other brands.
This is less of a compliment to (a branch within) Lenovo, and more of an insult to other brands; production quality for computers and laptops is absolutely awful unless you pay a ridiculous amount of money for the "pro" branding.