tomshardware[.]com/peripherals/printers/brother-accused-of-locking-down-third-party-printer-ink-cartridges-via-firmware-updates-removing-older-firmware-versions-from-support-portals
If it's not too late already, the advice is to make sure your Brother printer is Not connected to the internet so it cannot receive the new update. The router we have lets us block any device from connecting to the internet, but also allows communication with any device on our home network. Brother is apparently following in the footsteps of Epson, HP, and to some extent Canon. If it is too late, and your printer has already updated, *hopefully* 3rd party ink that works with the new firmware will become available soon.