...1. What "buck" needs to stop here? By that, what problem for America is his fault...
a. lack of adequate preparations for and lack of effective leadership during the pandemic
b. rapid deterioration of our alliances
c. lack of effective leadership and action to quell nationwide rioting
d. rapid deterioration of the relationship between the Executive and the DoD
...etc... etc... etc...
...2. What problem for America is his fault? ...
Already answered, above. You repeat yourself.
...3. No wonder nobody likes you...
Excellent... I'm not here to make friends... I'm here to comment upon American political life... want a friend?... buy a dog.
...4. Blamed for what, exactly?...
Already answered, above. You repeat yourself. Again.
...See folks. Perfect example of a Dimwinger whining and crying that it's all Trump's fault............yet can't give a single example. Not one.
Well,
THAT didn't quite work-out the way you expected it to, did it, lightweight?

...and that was merely scratching the surface, in this context.
What you Rumpian Minions don't "get" is that
ANY President is blamed for damned-near everything that happens on his watch...
Regardless of whether it's truly his fault or not... he gets the blame... he has to Man-Up and take it on his shoulders... fair or not...
Just ask the ghost of Herbert Hoover, who had to shoulder the blame for the onset of the Great Depression, even though it wasn't his doing...
In 2020 we saw a massive Stock Market Crash, 401(k) depletions, 40,000,000 unemployed, a pandemic, 120K+ dead, nationwide rioting, etc...
All the while, Cadet Bone Spurs is whining and crying that it isn't his fault, like some errant ten-year-old, rather than shouldering it like a Man...
The ghost of Herbert Hoover... a fellow Republican... is laughing his a$$ off at your Orange Baboon-God... and at you for supporting such a POS...
You'll understand all this better on the morning of November 4 2020, I expect...