I’d still like to know the details on the “cheapo” tires that the OP bought, even though they are unlikely to be the cause of the problem.
Now here’s some very simple questions
Are you a homeowner?
If so, I imagine you have a garage
In that case, you head over to home depot and buy a pancake air compressor and an inflator gauge
And you can check your tire pressures every weekend . . . say sunday morning, when you walk out of the house to retrieve the newspaper
If everything’s fine, no need to fire up the pancake air compressor
If one or more tires need topping up, fire up the pancake air compressor and take of business yourself
No need to schedule an a trip to the mechanic . . . at least not for that
Here is another gadget to consider, pump and battery charger. I have used the jump starter a few times, the pump many times
Buy a bicycle pump. I add a PSI to my 195/75R14s with 10 strokes, which takes about 10 seconds. I spend more time setting up than pumping. Unless I have a leaky tire a tire loses a PSI a month. I’d spend more time plugging a compressor in. I have a bicycle pump because I have a bicycle. I carry a foot pump in my pickup because I used to drive into distant remote places for long times, needed to repair my own problems. It’s slower and less wieldy, but takes up less space and doesn’t expose my hands to cold, which matters when it’s really cold.
Is this your first vehicle with a tire pressure monitor?
It is common to find the tires up to 10 PSI low at the time of service, pressure loss is normal, we just don’t make a big deal about it, it is our job to fill the tires, no need to scold the customer.
It seems that they want you to buy two more.