A tokenized stock is not a share. That is true of every tokenized stock on this site, and of every one we are aware of anywhere.
Who holds a share, if anyone, has several answers, and they depend on the wrapper. For a debt security, the token is a claim on the issuer, not on a specific share. The sections below go through each structure.
The certificate structures
Backed, through xStocks, issues tracker certificates, and Dinari issues dShares. Each publishes its own statement about what is held behind a token and who holds it.
This page does not repeat those statements. A statement about what backs a token is the one most likely to change without anyone noticing, and a stale copy of it looks exactly like a current one. Each issuer page links to the issuer's own documentation, which is where to read it.
The SPV structure
Ondo Global Markets issues through a bankruptcy-remote special purpose vehicle and states its tokens give economic exposure similar to holding the share and reinvesting dividends, rather than title to the share. Ondo describes them as total return trackers.
The vehicle sits between you and whatever it holds, and what you are promised is the economic outcome.
Coinbase also issues through a special purpose vehicle: Coinbase Onchain SPV Ltd., registered in the Abu Dhabi Global Market, for its tokens on Base. What that vehicle holds, and what it promises a holder, is set out in Coinbase's own documentation.
The debt structure
Robinhood states it issues its stock tokens as debt securities through Robinhood Assets (Jersey) Limited. A debt security is a claim on the issuer.
Here, asking "which share is mine" has no answer, because that is not what the instrument is. What the issuer holds, if anything, is set out in Robinhood's own documentation.
We want to be careful here, because it is easy to make this sound like an accusation. Robinhood published this structure, and an issuer cannot object to its own disclosure. A debt security is an ordinary financial instrument. The useful point is that it differs from a share held for you in an account, while the price on the screen looks identical either way.
This is less exotic than it sounds
Most people who own shares through an ordinary broker do not hold them either. The broker holds them, and the company's register shows a nominee where your name might be. That is called street name, and it is how the large majority of retail share ownership already works. Direct registration, where your name is on the company's books, is the exception.
"Someone else holds the share" is old news about the world. What is new is that the someone else, the legal form and the mechanism differ from the ones your broker uses, and that they vary between issuers of the same stock.
Where to check
Every stock page names the issuer for each token and prints the wrapper. Where one stock has tokens from several issuers, it has several rows, because those are several products with several answers to this question. The issuers list names each issuer's wrapper and links to the issuer's documents, and the glossary defines custodian, street name, direct registration and transfer agent.
Every claim about an issuer above is that issuer's own description of its product, linked above.