The Bug:
When a player performs any type of attack, that being a sweeping, weak, strong, knockback, or critical attack, the entity they harmed would normally receive some knockback, however, players can use shields to completely negate any incoming knockback that was inflicted by other players.
Due to the uprising of MC-223238, this had persuaded me to believe that this could potentially be an issue.
Steps to Reproduce:
Get two players and label them "Player A" and "Player B".
Have "Player A" switch into survival mode, obtain a shield, and begin blocking with it.
Get "Player B" to attack "Player A" with a knockback (sprint) attack.
Take note as to whether or not players receive any knockback when blocking other players' attacks using shields.
Observed Behavior:
Players don't receive any knockback when blocking other players' attacks using shields.
Expected Behavior:
Players would receive some knockback when blocking other players' attacks using shields.
Related issues
relates to
Comments

Hi @unknown, not quite.
MC-147694 talks about how mobs don't get repelled (aren't pushed back a bit), when their attack is blocked through the player using a shield, whereas this report (MC-248310), talks about how the player who blocks another player's attack using a shield, doesn't receive knockback. See MC-223238, as this may help in understanding this ticket. 🙂
Thank you for your report!
After consideration, the issue is being closed as Working as Intended.
Please note, that mechanics of the game may change between updates.
Things such as graphics, sounds, world creation, biomes, redstone, villagers, and animals may not work the same in current versions.
Full Version History – Snapshot Version History – The official Minecraft feedback site
Quick Links:
📓 Bug Tracker Guidelines – 💬 Community Support – 📧 Mojang Support (Technical Issues) – 📧 Microsoft Support (Account Issues)
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki
Duplicate of MC-147694