THANK YOU SO MUCH, OldSpot!
I had this exact problem after updating to 15.3.2 (directly from Ventura) and it's been haunting me for a week. Brother's site had absolutely nothing about this failure to connect with Sequoia and my ads-4900w scanner, and I haven't been able to find single reddit post about it either.
The only way I could use the scanner at all was to plug a flash drive into the usb port on the back. Not fun.
Sure enough, as soon as I followed your advice to enable Brother's iPrint&Scan in the Privacy and Security setting under Local Network, everything is working like a charm!
Meanwhile, I'd gotten around it for testing purposes by using the trial version of the proprietary VueScan app, and that got straight through. I'd been about to pay their $49.95 to get my scanner working again. Thanks, too, Ronasara, for suggesting VueScan as an alternative. As you say, the trial version does include have the watermark on every page, and is useful for testing only.
Til then, I really did my the scanner itself was broken. It's only a couple years old.
What bugs me most is that Brother has NO information about the permissions issue on its own site, and iPrint&Scan's onscreen error message just says it can't connect, period. Just as bad is that VueScan had enabled this in Privacy and Security by default, but Brother's iPrint&Scan software had not. That's even after I'd uninstalled the version I'd been using, and reinstalled with the latest version downloaded from their site. Until this, I'd had no problems using iPrint&Scan, at all.
Oh, Brother.