It is quite new to me that it is 134 bits on electrum, I only thought what is different about the seed phrase between Electrum and BIP39 is how they are generated, inclusion of version number to Electrum seed phrase during generation, I do not know if the entropy is not the same.
132 bits of entropy, not 134.
In a seed generated by electrum, there is no checksum. So, unlike a BIP39 seed phrase (in which the last 4 bits are checksum) in a electrum seed phrase, all 132 bits are generated randomly.
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here and read the post made by o_e_l_e_o in another thread.