Do not let anyone knows your seed phrase. Open source or close source wallet can not help against the person that knows your seed phrase because the person can steal your coins.
The benefit of open source wallet is that the public know its source code, unlike close source wallet that its source code is only known to the developers that created the wallet, and vulnerabilities can be included which the public can not know about.
After reviewing the replies, I believe you have all the technical answers. What I write now is a simple knowledge that most of us forget. it's crucial to remember the following steps to improve security, such as using strong passwords, enabling two-factor authentication, and keeping your devices and software up to date. Do remember that backing up your seed phrase and storing it securely offline is one of the most important steps. If you follow the above steps, you will never be going through any anxiety about losing your cryptocurrency.
The question asked by the OP is not about the general security of the wallets. You can keep your seed phrases to the safest place on the earth, keep your devices virus free, take every precaution with a closed source wallet and still the owners of the wallet can steal your funds if they make changes in the code to get your seed phrases.
Now you know why we are discussion here the open and close source wallets and not the general security. First you need to transfer funds to the reputed open source wallet and then make all the measures to safe guard your wallet.
