My '78 FJ40 did this after 40 years (on the original front calipers) and I rebuilt the calipers and it went away. The pistons were not rusty, but had serious sludge on them, causing them to hang up. Rebuilding 4 piston calipers is a messy pain in the rear.
My '89 FJ62 is now doing this, and I plan to do the same. The reman calipers from Toyota are $56 each, but were back-ordered of late. As @ceylonfj40nut said, it could be the rears, too, but I tend to think it's rusty or gummed up front calipers. YMMV.
Make sure you bleed the system in the order laid out in the FSM.
Also adjusting the drums but adjust automagically with the parking brake, so give the parking brake handle a couple cranks up and down.
Maybe look at swapping the bleeder to speed bleeders. I had the same issue even with a vacuum bleeder. Tried coating the bleeder threads in Teflon tape and putting grease around the fittings, but always seemed like I was pulling air past the bleeder threads. The speed bleeders fit much better.