UUPS Proxy Security Concerns

I set uups proxy's upgrade permission using some like function _authorizeUpgrade(address) internal override onlyOwner {}, which is suggested by UUPS Proxies: Tutorial (Solidity + JavaScript)

Then I found out that the actual proxy admin slot in ERC1967Proxy is not used that way. That means the upgrade permission is only controlled by _authorizeUpgrade() function, rather than the proxy admin, which is suggested by ERC1967 standard?

Although the current contract upgrade works fine, I'm wondering if there could be any possible issues?