Steps to reproduce

1. Make a spawn platform or enclosure to collect mobs.
2. Somewhere on the platform, set up a minecart next to a dispenser.
3. Put equipment in the dispenser.
4. Allow zombies to spawn naturally on the platform.
5. Push a zombie into the minecart.
6. Activate the dispenser, e.g. by placing a redstone torch next to it.
7. Send the equipped-zombie-in-minecart down a long minecart track, or fly away, so that it is beyond the instant despawn range.

Expected result

The zombie does not despawn.

Actual result

The zombie despawns.

Notes

• This seems inconsistent with the fact that the same mobs would gain persistence by picking up dropped equipment.
• On the other hand, strictly speaking this is consistent with the fact that mobs are supposed to gain persistence only from significant player interaction, and dispensers are not players. Compare MCPE-110521.