Rails + Apache = 429 (Too many requests)

Question

I have a Rails 7 application that runs on a Docker container. I configured Apache to reverse proxy incoming requests to the container. Everything works fine, except that in specific pages that I need to load many images (~100 user profile images), I get many 429 (Too many requests).

I configured Apache with

<IfModule mpm_prefork_module>
  StartServers              5
  MinSpareServers           5
  MaxSpareServers           50
  MaxRequestWorkers         200
  MaxConnectionsPerChild    10000
  MaxRequestsPerChild       0
</IfModule>
    
<IfModule mod_headers.c>
  Header set Retry-After    "15"
</IfModule>

but I'm still getting the 429's.

Any tip?