Eww can't searx (?)

Hello,  it seems that one of the most often recommended ways to 
search the internet - using "Searx" (a metasearch engine) cannot 
be used with the built-in browser of Emacs - EWW.  Because, when I 
do that, I get the response "Too many requests" each time.   The 
thing is that this is not as simple as it seems: I do get a normal 
response at the same moment when using w3m or Firefox.  The way 
the connection to the Searx server is established seems to play a 
role here.  This seems to have already been noticed by others. 
But I don't have the insights into this matter to investigate it further.   Does somebody have a solution for this problem?  Is there 
anything we could do or change from the Emacs side (`browse-url'?) 
to avoid this kind of problem?    TIA,  Michael.