I don't think it is hard to understand.
The definition is available for all to compare their comments and perceptions.
For instance, if RL-B had thought to consult the definition, say this one:
“Antisemitism is a certain perception of Jews, which may be expressed as hatred toward Jews. Rhetorical and physical manifestations of antisemitism are directed toward Jewish or non-Jewish individuals and/or their property, toward Jewish community institutions and religious facilities.”
https://www.holocaustremembrance.com/working-definition-antisemitism
She would have also seen:
However, criticism of Israel similar to that leveled against any other country cannot be regarded as antisemitic. Antisemitism frequently charges Jews with conspiring to harm humanity, and it is often used to blame Jews for “why things go wrong.” It is expressed in speech, writing, visual forms and action, and employs sinister stereotypes and negative character traits.
Clearly, the tweet served to blame Israel for the methods used in the death of George Floyd. The fact that it was not true doubles down on that. Therefore it was undoubtedly anti-Semitic.