On the one hand, you should be commended for uploading 13 hours of log file data. I usually have to beg people to see some data.
On the other hand, I have no idea how you had ThrottleStop setup during your 13 hour session, I have no idea if you made any changes to ThrottleStop or to your Windows power plan, or what exactly you were doing at any point during that log.
Early on, the CPU multiplier is spending most of its time in the 40 to 42 range which is what it should be doing. When you put a load on the CPU, it drops to a steady 40 so that all looks fine. Throughout the day and into the early evening when it looks like you are not using your computer, the multiplier is OK. No problems.
Just before 7 PM, the load goes up slightly and now the maximum multiplier is limited to 40.00. I have no idea if you sat down at your computer and clicked on the Disable Turbo feature or what happened. All I see in the log is that Turbo Boost is now disabled. I was not there so not sure why.
If you switched to a Windows power plan that has the Maximum processor state set to 99% or less instead of 100%, that will disable Turbo Boost.
At 9:25 PM, the load starts to change and Turbo Boost starts working normally again.
Just before 11:00 PM, for the first time, I start seeing the CPU multiplier drop down around 35. Not sure if you changed to the Windows Balanced power profile or what happened. The VID voltage is normally up around 1.21 - 1.24 V. When the multi drops, I start seeing the odd VID reading in the 0.7150 to 0.7250 range. That is more confirmation that something like the balanced power profile is trying to kick in which is lowering your multiplier and voltage. Depending on how you have ThrottleStop setup, it might be fighting against Windows trying to keep the multiplier high even though Windows wants it low.
All in all, something is not quite right. Without knowing exactly how you had ThrottleStop setup or what sort of changes you might have made while testing, it is impossible for me to come to any conclusion. Maybe instead of throwing 13 hours of data at me, show me how you have ThrottleStop setup, make sure you are using the Windows high performance power profile with the Minimum processor state set to 100% and then go play a game. Send me a log file of whatever but give me a few more clues about what that log represents in terms of usage.
As for your other question, when a CPU is lightly loaded, individual threads and cores will be constantly entering and exiting various C states. This is why the multiplier reported for each thread is going to be slightly different from thread to thread. On a lightly loaded CPU, there is no way for all 8 threads to be doing the exact same thing and all 8 threads to be spending the exact same amount of time in each C state. Some variation from thread to thread is 100% normal. The multiplier number reported by ThrottleStop for each thread is a very accurate average during each 1 second sampling period.
In the C0% column, if ThrottleStop shows 1.0, that means the CPU was in the C0 state, actively working on something 1% of the time and the other 99% of the time, it was idle in one of the other low power states doing nothing. The CPU will first go into C1 when it has nothing to do. If C1E is enabled, then it will use that. If still nothing is going on and the CPU does not have any tasks that need to be completed, then it will drop down into C3 or C6 or C7. I think some CPUs drop down directly from C0 to C1 to C7. They might also do the opposite and go from idle in C7 and jump right back into C0 so they can get to work immediately. Intel has made changes with each generation with their goal being CPU cores that can immediately get to work when needed and to go idle when not needed. This is the best way to save power.
Your ThrottleStop idle data looks great. In the pic it shows 1 thread at 0.3% or 0.5% or 0.6% in the C0 state, working on Windows background tasks while the second thread for each core is reporting 0.0. The load on the CPU is very light so there is no need to have both threads active. Windows is letting the hyper thread for each core sit idle. When the load starts to increase, there will always be a primary thread doing more of the work compared to the secondary thread. At any point in time, either thread can be the primary thread.
In the Options window, try checking the Add Limit Reasons to Log File option. If you were not changing the Windows power plan, this might show why your CPU was throttling and will add that info to the log file.