My new Bose Qc 35 II. I have tested both this and sony XM4 and gone with Qc35II.So much happy specially with 4.8.1 firmware. I wonder it is competing with 2020 XM4
Bose Now Lets You Downgrade Firmware of QC 35 If You're Facing ANC Issues | Beebom
How to update the firmware of your Bose Headphones/Earphones, Speakers, etc. on your computer ? - YouTube
Downgrade your Bose QuietComfort 35 II from any version to 4.3.6, 4.1.3, 3.1.8, 3.1.7, 2.5.1, 2.2.1, 2.2.0, 2.1.3 or 2.0.1 : r/bose
Updating the software or firmware of your product - Bose on-ear wireless headphones
Bose QC35 II owners complain of degraded noise cancellation after recent updates - The Verge