[Yelp Search API] Increased response time and failed requests

[NateSkiles]

The customer that reported #1835 followed up with examples of failed requests, but as they were using the Yelp engine and not Yelp Place, I've opened this issue separately.

I tried to recreate the failures the user received in the playground, but was unable.

"error": "We couldn't get valid results for this search. Please try again later."

Search Inspector:

• Search 1
• Search 2
• Search 3

In addition to these searches, I'm seeing an increase in failed requests and response times starting yesterday (8/12) on the Yelp engine:

• https://serpapi.com/status/yelp

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