If you’re just starting out with vo2 work, 3 minutes at ~123% is pretty difficult. doing vo2 on the turbo is harder than it is outdoors too.
When doing vo2 work on the trainer, I would often get psyched out by intervals longer than 2 minutes, because I knew it was going to hurt. Maybe try starting out with 30/30s, these are less daunting I find, but they are pretty well regarded as being effective, as far as I’m aware.
Don’t let it get to you, your progress won’t be linear, and you’ll have off days. Maybe it was just an off day, but as I said previously I’d rate any intervals over %120 at the hot end of vo2 work.
Don’t be discouraged, if you are able to, maybe try doing the intervals outside on a climb, if you can’t do that, try 30/30s and work up to longer intervals. 3 mins at 123% is hard, if it felt easy something’s wrong. Sometimes TR gets it wrong, don’t worry.