If it were me, I’d think it was a combination of accumulated fatigue and muscle soreness/stiffness from the previous 2 hard efforts. Are you getting in decent cooldowns at the end of your more intense rides (I almost never do, and have probably suffered because of it for a long time)?
I’ve also, so many times, ridden really hard with my friends on the weekend and took Monday off so I could do intensity on Tuesday, and felt really flat come Tuesday…but finally learned that if I do an easy spin on Monday, I feel fresher on Tuesday (which may not have been needed if I did a proper warmdown on Sunday?).
How is your recovery? Are you getting plenty of protein and carbs, and rest/sleep? Sometimes, the day after a hard ride, when my legs feel flat, and I’m doing an easy spin or zone 2 ride, a gel will wake them up nicely (this works for me more often than not on outdoor rides, too, when the intensity is high and I don’t realize I haven’t been keeping up with carb intake).
I’ve finally gotten to a stage of having a solid base fitness, but before this it would take me forever to feel warmed up sometimes (and I was pushing too much intensity at the time). I’d go on a MTB ride on a particular 8.5 mile/45ish minute route with my friends and my legs would feel flat and stiff until all of a sudden, at mile 8, starting up the series of climbs back up to the trailhead, my legs would feel fantastic. I say this as maybe extending (and/or decreasing the intensity of) those 30 min endurance sessions you’re doing could make the difference.
And lastly, you might need a day off, and/or reduce to 2 days of intensity per week might be your sweet spot. That schedule doesn’t look much like high volume (is it reduced because you’re in specialty phase?), so are you now coming off a build phase that was 15 hour weeks or something? Many of us have run ourselves into the ground trying to do too much intensity every week (I did it a few years ago trying to increase up to 7 hours a week…my friends were suddenly getting faster and I was getting slower and couldn’t keep up anymore). Didn’t seem right that I could be overreaching or overtraining at 6 hours per week, or 4 days of 1.5-2 hr outdoor mtb rides. Took a lot of z2 days to dig out of that hole, but 2 years later most of my friends are trying to keep up with me, and I almost always feel good when it comes time to pedal.
Sorry I’ve run on so much. Hopefully something in here gets you where you want to go. 