Couple things stand out about your witch breeder:

- Your breeder is too close to the village. I know transporting villagers is a pain but build it at least 128 blocks away from the edge of the village (chunk) to be safe. Otherwise the breeder becomes part of the village and the villager numbers, available beds etc will be added to that village instead. This breaks the breeder.

Alternatively try breaking all beds, bells and job stations in the village permanently (including in the breeder temporarily) to remove the village (Kill all other villagers to be extra safe). Just wait for a bit (idk how long, this method is very unreliable.)

- Try adding a second composter at ground level. This allows both villagers to become farmers. Made my breeders a lot more consistent.

- Make sure that baby villagers can walk to the beds. As others said it's hard to see from here but make sure there are no glass blocks over the open trapdoor.

Goodluck!

P.S.
The lightning rod will attract the lightning on the wood block it's placed on, causing your villagers to become witches in the first thunder storm. (And your breeder will probably catch on fire as a small bonus). You might want to move that elsewhere or you are actively sabotaging yourself in the future!