First thing you need to know is how it works.
The cooling system has coolant in it, and is subject to temperatures ranging from roughly -10F to 250F. What do we know about temperature changes? Expansion. And contraction. Heated fluids tend to try to expand. Cooling fluids tend to lose the expansion, e.g. "contract". Your coolant is 50% water 50% ethylene glycol.
The radiator has a cap on it. That cap is not just a little dealie that holds coolant in. It's a pressure cap. Under the cap on the radiator is a nipple, with a hose on it, that leads to an overflow bottle (sometimes called a puke tank). The pressure cap works two functions. One, it allows pressurized coolant that is over the pressure cap's rated pressure relief, to escape to the puke tank. But, what many don't realize is that is also is a recovery cap. As the coolant cools down, it contracts. Remember that little bit of coolant that puked into the tank? As the system contracts, it will also open the cap's valve and allow coolant to be drawn BACK INTO the radiator, thus keeping the system full and mostly bled of any air (if everything is perfect).
So, what you have now, is a system that is bleeding itself of air, the pressure rises, pukes a little air and maybe a little coolant into the puke tank. Then as it cools off, it's drawing coolant back into the radiator from the tank, and your tank level will drop a little. After 230 hours worth of work (which seems high for a 2021 BX?) and 230 hours worth of heat cycling, yeah I can see it pulling quite a bit of coolant back in, especially now with winter in full swing in a lot of states (again, temp difference between summer and winter can cause this to happen too).
If after you clean the tractor up well, and run it to operating temp, then shut it down, and you don't see any evidence of any leaks, let it cool off, check the coolant in the radiator, refill if it wants any, then top the tank off and see what happens. You ever smell any coolant while running? Radiator ever been cleaned? Screen ever been cleaned?
it is perfectly normal for the tank to show low after a few heat cycles. Don't panic. If u cant see or smell any leaks anywhere, just refill it and go on about your business. That's awesome that you're actually checking it. most people don't. Be sure to keep the radiator and screen clean too.