It depends where you are looking. Unless it gives a timezone (which is usually the case where it is Pacific Time) it is most likely your timezone, but that is not guaranteed.
Each page on ebay.com displays auction endtime time differently, and other means of accessing eBay data have their own preferences. (Display is different than the actual time that eBay keeps internally, which is in a machine code based on the number of seconds since a particular UTC time to a fraction of a second.) Thank all the people who complained about having to convert from Pacific Time to Whatever Time (and asserting it would be SOOO easy for eBay to do it for them) for this mess. Last I checked (3:58 pm CST 1/8/2022):
On the Search Results, eBay attempts to display the time in your local timezone (which it apparently gets from your system settings, so that if you left your computer on the default Pacific Time when you bought it but set the time to your local time, the endtime will be in Pacific Time but the "time left" will be off, including showing listings that are still running as ended), in 12 hour format truncated to the lower minute without an indication of what timezone it is. (Tue, 08:42 AM; but note that if you sort by "Time: Newly Listed" the time of listing is in 24 hour format)
On the My eBay pages (Bidding, Watch List) the endtime is in Pacific Time (but no longer says PST or PDT: Tuesday, 06:42 AM ) in 12 hour format truncated to the lower minute.
On the Listing Page for the item being auctioned the endtime attempts to be in your timezone (see the explanation for search results, but the "Time left" is calculated differently so it is relatively accurate) in 12 hour format truncated to the minute with no timezone display ( Tuesday, 8:42AM). This causes much confusion (sometimes anger) in people who expect it to end at the beginning of that minute, and then get outbid during the period between the beginning of the minute and the actual endtime.
On the Bid History Page bid and cancellation/retraction timestamps are truncated to the second (but eBay keeps the time to a small fraction of a second to be able to break ties) in 12 hour format in Pacific Time (PST in Winter; PDT in Summer; remember that 12:59:59 is prior to 1:00:00 when comparing bid times). However, for an active (as opposed to an ended) auction the scheduled endtime is not directly displayed: if there is an active bid it can be calculated by adding the "Duration" to the start time (next to the amount of the starting bid at the bottom of the active bid list: 6 Jan 2022 at 6:42:32am PST; unfortunately that line doesn't show if there are no active bids). When the auction is over the actual endtime (whether it goes the full duration or is ended early by the seller or by a Buy It Now or Best Offer sale) is displayed, but unfortunately in May, 2022 there was another reformat of the page which truncated that display to the lower minute (but left the bids displayed to the second, further inflaming those angry at losing to--or winning but having the price raised by--a bid timestamped during the last minute).
On the Android App I have all times that are showing are attempted to be shown in the device's local timezone in 12 hour format truncated to the minute.
On other eBay country sites it differs (unfortunately not as much as it used to: the Listing Page on ebay.co.uk still displayed seconds until Spring 2022, but then got reformatted to match the ebay.com truncation)
To see and compare what times are displayed on the various pages on your device, do a search and find an auction with at least 1 bid on it that looks like it will end mid-morning (to avoid having to convert 12 to 24 hour, though that seems no longer an issue) in a few days. Note the endtime display there. Click on that listing and note the endtime display on the Listing Page. Put the listing on your Watch List then click on the # of bids to go to the Bid History Page and add the "Duration" to the starting time and note that. Then go to your My eBay: Watch List and note the time there. If you use a mobile app (which I don't recommend relying on for anthing of importance) check the various time displays there for the same listing.
If the search result or Listing Page (or the mobile app) shows the same hour as the Watch List and the Bid History (and you are not in Pacific Time) check your system settings (in Windows click the time display on the taskbar, click the "Change date and time settings" link and look on the timezone tab to see if you've got it set for Pacific, and change if you want the search results and Listing Page to show in your timezone, then reset the time to accurately show your local time (or better, use the internet time feature to synch to a time server) and save the changes.
