It is true that Electrum is an open-source wallet due to its open-source nature. As a result, the source code of the software is publicly available, allowing developers and users to review and verify the software's security and functionality. The security of open-source projects can be enhanced by the contributions and audits of the community.
You should consider your needs and preferences when selecting a wallet. With hardware wallets, such as Trezor and Ledger, private keys are stored offline, making them less vulnerable to hacking and malware attacks. When storing significant amounts of cryptocurrency or storing long-term, hardware wallets are often recommended.
Now come to the point, whatever software wallet or hardware wallet, whatever Trezor/Ledger or Open-Source, who knows do they have any back door or not? ?
I always prefer Bitcoin core wallet with an offline machine(Linux/other os), or at least DIY Crypto Hardware Wallet is more safer than Trezor and Ledger...
Sure, open-source projects have the advantage of community audits and transparency, but that doesn't mean we should let our guard down. Even with Electrum's open-source nature, we can't be 100% certain about the absence of backdoors. It's a constant battle between convenience and security. For me, I'd rather take the extra steps to ensure my funds are in the hands of a wallet I have full control over, like a Bitcoin core wallet on an offline machine.