Biden sucks at foreign policy and has never been good at feeling the pulse of foreign leaders. That's been true his entire career, but until January 2021, he had little direct influence on that.
However, the problem goes even deeper.
Think about the ideal opponent at the poker table. You don't want an unpredictable maniac, because that person can be hard to read and hard to counter, even if overall you are +EV against them. The ideal opponent is one who is a combination of weak, confused, and predictable. When you're against an opponent like that, you always know where you are against them, and you can pretty much lead the action.
That's also what foreign leaders think of Biden. Not only do they realize that he's a senile old coot, but they know that Democrats in general are weak and predictable when it comes to foreign policy, so it's easy to both push them around and predict what they're going to do next.
Trump was kind of seen as a maniac. He beat to his own drum. He had a big ego. You never knew what he was going to do. Combine that with the fact that Republicans in general are more willing to use military force, and foreign leaders didn't want to fuck with him. Look at the difference between how Iran handled Obama versus Trump. They actually extorted $400 million out of Obama for a hostage return, and then bragged about their victory after the deal was done. In January 2020, Trump killed their beloved general Soleimani, and they were so terrified to strike back that they actually let the US military know they were about to fire rockets at their base, so everyone could get out safely.
It is not at all surprising that all of this foreign aggression has occurred over the past 14 months while Biden was in office, whereas none of it occurred under Trump's 4 years in office. Putin has been talking about doing this to Ukraine for many years, but he chose now instead of during Trump's term. There's a reason for that.
I won't even get into the crisis on the border with Mexico -- another direct response to Biden's perceived weakness, but this time by immigrants rather than governments.
Trump was actually great at foreign policy -- far better than I expected, actually. Biden has been horrible, and in fact worse than even the low expectations I had set for him.
Actually if you go back to the period when Obama was searching for a vp, foreign policy experience was touted as his greatest strength, which Obama lacked. Not saying it’s true. But that was the word then.