What is a “fillipo of” meant by the above sentences?

Does No.1,2, and 3 have usage examples from other dictionaries? What if we polled low

1. even before the months of violent “Yellow Vests” protests erupted late last year?
2. When Pascoe noticed her husband’s voice, she knew that she had no secret, and it was a shock. From the moment she was left, she didn’t know his voice.
3. Does the young woman feel good just because of a more than pleasant neighbour?
4. To this day, though, the mention of crows produces a little fillip of panic in me.

What is shown below are the relevant definition of fillip I have found from various dictionaries.

Oxford dictionary = something which acts as a stimulus or boost to an activity.

What triggers sudden improvement?

Language Terms. Vocabulary. Dictionary: anything that tend to arouse As

you can see with fillip means along the lines of a boost or a stimulus. Only Merriam & Webster dictionary uses two additional meanings that might be helpful.

a a trivial addition c a significant and often unexpected development

However I am still confused about the meaning of fillip in the above 4 sentences. Is it possible to boost the support of president by the President’s death? What does fillip mean in 2 and 3, but I have no idea what they mean by you in a 2 and 3 sentence? I think 4 means panic. What is it?

What is the meaning of “assess or protect”?