I’ll let others comment on the zones, etc but i am more curious of your HR profile during the intervals. In a 12min SS effort, you should have a level HR. It’ll start lower of course but it should level and stay flat for more the half of the interval. These are fully aerobic and sub-threshold efforts that should not be a gradually climbing HR. If you consistently see your HR climb throughout the interval, it is more likely you are therefore closer to threshold and your FTP may be set on the high side.
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It looks like you’re working at Threshold not SS. Your HR is too high. SS should call for you to be focused on the effort with your HR below what you would see if you were at race pace/threshold. As a time trialist with an HRmax about 181 I would race around 166bpm and on the trainer indoors only see 160-163bpm at the end of a second 2x20 minute SS interval. Your breathing should be hard but steady. If your breathing is getting ragged and gasping you are definitely working too hard for SS.
As the last 2 said, it seems like your ftp is possibly too high, and you’re operating at or above threshold, causing much more drift than you should have in SS. It’s also very possible that your LTHR wasn’t estimated correctly and is set too low, making the output seem more extreme.
I’d do a LTHR test and get your LTHR dialed in, so you can at least recognize what is happening on stuff like this. Oh, my zones and the corresponding RPE are quite a bit different from inside to outside, too (I don’t have power on my mtb).