user76592: I'm running pre-release version d8dad7 of Electrum that supports BIP-84 HD derivations.
When exporting private keys, I'm getting WIF keys that are different from the expected output generated by bx or iancoleman.io/bip39.
Example
Create a new Electrum wallet by importing the mnemonic tumble mistake gift ill hungry chunk suggest limit artwork filter peanut exhaust with path m/84'/0'/0'.
The first pubkey (m/84'/0'/0'/0/0) is correctly generated:
0300e0d90c8cb3e1bb7b7a82bd1a118c615d97c03dd3c5f607636e9305a22bbd3e
bx shows the same key:
mnemonic="tumble mistake gift ill hungry chunk suggest limit artwork filter peanut exhaust"
echo $mnemonic | bx mnemonic-to-seed | bx hd-new | bx hd-private -i 84 -d | bx hd-private -i 0 -d | bx hd-private -i 0 -d | bx hd-private -i 0 | bx hd-private -i 0 |bx hd-to-public | bx hd-to-ec

In Electrum, the corresponding private key (Wallet -> Private keys -> export) is displayed as LEF3hMKjm4E1MVsGZLpPb5Bjza8p7qqRYn4GzjyCK8Uo1CX8w3z2.
But bx ...
 echo $mnemonic | bx mnemonic-to-seed | bx hd-new | bx hd-private -i 84 -d | bx hd-private -i 0 -d | bx hd-private -i 0 -d | bx hd-private -i 0 | bx hd-private -i 0 | bx hd-to-wif

... (like iancoleman.io/bip39) gives another result:
L5fR8BxqauJsNyrW1GRVnu6Fk8wAHRZhPLS9SHd6pej5isKt3qJH
Is this a bug in Electrum or an export scheme that differs from the regular WIF?
This discrepancy in private keys doesn't appear when using m/44'/0'/0' as the derivation path in Electrum.

user76592: Electrum uses a modified WIF that encodes the address type:
Release notes
Source

76592: <p>I'm running pre-release version <a href="https://github.com/spesmilo/electrum/commit/d8dad74267fe1bdcd98dce0d79e2196f7ced60dc" rel="nofollow noreferrer">d8dad7</a> of Electrum that supports BIP-84 HD derivations.</p>

<p>When exporting private keys, I'm getting WIF keys that are different from the expected output generated by <a href="https://github.com/libbitcoin/libbitcoin-explorer" rel="nofollow noreferrer">bx</a> or <a href="https://iancoleman.io/bip39/" rel="nofollow noreferrer">iancoleman.io/bip39</a>.</p>

<h3>Example</h3>

<p>Create a new Electrum wallet by importing the mnemonic <code>tumble mistake gift ill hungry chunk suggest limit artwork filter peanut exhaust</code> with path <code>m/84'/0'/0'</code>.</p>

<p>The first pubkey (<code>m/84'/0'/0'/0/0</code>) is correctly generated:
<code>0300e0d90c8cb3e1bb7b7a82bd1a118c615d97c03dd3c5f607636e9305a22bbd3e</code></p>

<p><code>bx</code> shows the same key:</p>

<pre><code>mnemonic="tumble mistake gift ill hungry chunk suggest limit artwork filter peanut exhaust"
echo $mnemonic | bx mnemonic-to-seed | bx hd-new | bx hd-private -i 84 -d | bx hd-private -i 0 -d | bx hd-private -i 0 -d | bx hd-private -i 0 | bx hd-private -i 0 |bx hd-to-public | bx hd-to-ec
</code></pre>

<p>In Electrum, the corresponding private key (<code>Wallet -&gt; Private keys -&gt; export</code>) is displayed as <code>LEF3hMKjm4E1MVsGZLpPb5Bjza8p7qqRYn4GzjyCK8Uo1CX8w3z2</code>.</p>

<p>But <code>bx</code> ...</p>

<pre><code> echo $mnemonic | bx mnemonic-to-seed | bx hd-new | bx hd-private -i 84 -d | bx hd-private -i 0 -d | bx hd-private -i 0 -d | bx hd-private -i 0 | bx hd-private -i 0 | bx hd-to-wif
</code></pre>

<p>... (like <a href="https://iancoleman.io/bip39/" rel="nofollow noreferrer">iancoleman.io/bip39</a>) gives another result:
<code>L5fR8BxqauJsNyrW1GRVnu6Fk8wAHRZhPLS9SHd6pej5isKt3qJH</code></p>

<p>Is this a bug in Electrum or an export scheme that differs from the regular WIF?</p>

<p>This discrepancy in private keys doesn't appear when using <code>m/44'/0'/0'</code> as the derivation path in Electrum.</p>
 76592: <p>Electrum uses a modified WIF that encodes the address type:</p>

<p><a href="https://github.com/spesmilo/electrum/blob/42a16d9c3e19785ad39f272517aa2ce54b9e0f7f/RELEASE-NOTES#L126-L139" rel="nofollow noreferrer">Release notes</a></p>

<p><a href="https://github.com/spesmilo/electrum/blob/42a16d9c3e19785ad39f272517aa2ce54b9e0f7f/lib/bitcoin.py#L524" rel="nofollow noreferrer">Source</a></p>
