Hi, I am using Bitwarden on Windows and in Chrome browser and I have noticed that if I click on ‘Manage passkey’ in Chrome
Unless the prompt to save a passkey looks like the screenshot below, then you are not saving the passkey in Bitwarden:
If you do not get a Bitwarden-branded pop-up (like the one shown above) when you try to create a passkey for some site, then there may either be a misconfiguration on your part (e.g., the domain may have inadvertently been added to the exclusion list under Settings > Excluded Domains), or your Bitwarden browser extension may have been locked or logged out, or there may be some incompatibility between Bitwarden’s passkey functionality and the website in question.
In such cases, you should not proceed with passkey creation if you do not want the passkeys to be stored outside of Bitwarden.
In addition to @grb you should also check, that this is turned on:
(source: Storing Passkeys | Bitwarden Help Center)
This is a good point. I had assumed that OP only had some passkeys that were being stored outside Bitwarden.
@Christop If those 6 passkeys stored in Windows represent every passkey that you’ve ever created, then the solution is most likely what @Nail1684 has pointed out — you need to enable the option “Ask to save and use passkeys” under Settings > Options in the Bitwarden browser extension.
@grb It sounded to me like @Christop may have never seen the Bitwarden-passkey-popup, that’s why I thought of that option… And I posted the link to the help site, because @Christop may want to have insights in how to create passkeys in Bitwarden, especially if he indeed never did this before… Either way - I hope @Christop found some answers here. 
I am actually using BW for my Passkey, and I did so even before the 6 Passkeys in Windows got registered :
My ‘Ask to save and use passkeys’ BW option was always selected.
Here are the details of the passkey I have in Windows: for these websites, I have my Passkey in a BW registered at first. I am ONLY using Chrome website to login where I have BW addon, how it is possible that I got that
In that case, the answer to your question is in my response above.
I have deleted almost all my Passkeys inside Windows:
For information before removing Passkey from Windows I had this screen (and it worked): as you said it was not handled by eBay
But now when I go to http://www.ebay.fr website, Chrome tells me there is “No passkeys available There aren’t any passkeys for ebay.fr on this device”, even though you can see that Bitwarden Chrome extension is unlocked and I have a login entry for ebay.fr website that has a Passkey:
Why is Bitwarden addon for Chrome not using the Passkey for ebay.fr I have in Bitwarden?
@Christop That seems to be a general problem of the eBay website. It seems to be designed, that it directly sends passkey requests to the OS (e.g. Windows Hello…) and third-party password managers can’t (or at least don’t) intercept this.
See, for example, here: Passkey popup doesn't show - domain not on excluded domains list and on the GitHub link therein…
And so, I would guess, your eBay passkey in Windows Hello was indeed used for eBay login. (as you read my text in the provided link, I was able to create a passkey for eBay in Bitwarden as well - but am not able to use it, as explained above and in my text in the link)
Thank you for the info, I thought it was me. In Javascript, how to force ebay to request Bitwarden? I would like to insert this in Userscript for the domain ebay.fr in help to solve this issue.
If there is no solution for eBay, how we avoid the “Use a passkey” prompt on ebay.fr login webpage:
I am having this prompt even though I have no eBay passkey stored in Windows:
As far as I understand it, this prompt comes from the (Chromium?) browsers. If you would open eBay via e.g. Firefox, this prompt is not there.
I also have this prompt in Brave. And in Brave, I have deactivated all password manager function. So, at least no obvious way to change this.
I am using the Chrome browser on Windows.
I have just tested on Edge browser (I think it is Chromium too) and there is no “Use a Passkey” prompt. I do not have Firefox installed.
Ah, interesting, that is not there in Edge. Right, so not every Chromium browser, as it seems. 
I am a bit surprised Edge does not too since this is Windows passkeys and Edge is a Microsft product. This would mean MS is not using the passkey system they have developed inside Windows.
