Able to withdraw even though owner not being set as payable

Smart Contracts
1

Hey all,
I'm testing UUPS locally with hardhat. In my "version 2" .sol I'm adding a "withdraw" function that is intended to withdraw the contract funds to the owner. I have a slight issue that I'm hoping someone can shed some light on for me. The withdraw seems to be working without explicitly giving the owner address "payable". I don't see where it is happening in the imported "OwnableUpgradable.sol" either.

My withdraw function:

contract Domains_v2 is Domains_v1{

    function withdraw() public virtual onlyOwner {
        uint amount = address(this).balance;
        
        (bool success, ) = msg.sender.call{value: amount}("");
        require(success, "Failed to withdraw Matic");
    }

(There, I wouldn't expect the msg.sender.call to be working even though we're satisfying the onlyOwner condition.)

My initialize function looks like this:

contract Domains_v1 is Initializable, OwnableUpgradeable, UUPSUpgradeable, ERC721URIStorageUpgradeable {

    // initializer replaces "constructor()" 
    function initialize(string memory _tld) public initializer payable {
        __Ownable_init();
        __ERC721_init("Pibble Name Service", "PNS");
        tld = _tld;
        //console.log("%s name service deployed", _tld);
        // console.log("I am also an UPGRADEABLE contract!");
    }

    // authorizes upgrades NEVER LEAVE THIS FUNCTION OUT OR YOU LOSE UPGRADABILITY!
    function _authorizeUpgrade(address newImplementation) internal
        override
        onlyOwner{}

It was my understanding that the owner has to be explicitly granted payable with something like this:

address payable public owner;

Then in the constructor (for non-upgradable contracts) you'd need something like this:

  owner = payable(msg.sender);

But I'm not doing that anywhere in my code, nor am I seeing it in the openzeppelin code. I'm probably just missing it, but can someone explain how my owner is getting the permission to withdraw the funds?

Thanks!