It is my understanding that you can't use (most) Electrum servers with a pruned node. It requires a full archival node.

AI explanation:

An Electrum server acts as a middleware or a bridge between a Bitcoin full node and a lightweight (SPV) wallet like Electrum, Sparrow, or BlueWallet.

Core Functions
Indexing: A Bitcoin full node (Bitcoin Core) is designed for validating the network, not for searching wallet history. It does not naturally index which addresses belong to you. An Electrum server builds an index of every transaction on the blockchain so it can instantly tell your wallet its balance and history.

Privacy: If you use a lightweight wallet without your own server, you are sharing your transaction history and IP address with a public third-party server. Running your own Electrum server ensures no one else knows which addresses you own.

Resource Efficiency: Lightweight wallets (mobile or desktop) cannot store 600GB+ of blockchain data. The Electrum server handles the heavy storage and computation on a dedicated machine (like a Raspberry Pi or PC), allowing the wallet to remain fast and portable.

Verification: It allows your wallet to verify that the transactions it sees are actually included in a block, using the security of your own full node rather than trusting someone else's.