Any form of instant mining is glitchy. Sometimes, blocks appear to be mined, but are invisible and cannot be walked through. The faster blocks are mined, the more frequent this occurs. Furthermore, the use of haste and/or highly efficient tools is problematic.

To reproduce this issue, simply dig tunnels in the nether using an efficiency 3+ diamond pickaxe.

This issue has been in Minecraft Java Edition for as long as I can remember, and I could not find any existing bug report on it.

Players must use slower tools (especially in the nether) to avoid this issue.