Haproxy TCP RST problem (node.js ECONN RESET)


we have (for long time) problem with TCP RST conection close between haproxy and backend (node.js)
its not about httpchk (we know its the default behaviour from 1.5 Repositories - haproxy.git/commit)

its about standard simple http GET
we have simple standard config like this

frontend example.com-in
bind ssl crt example.pem
timeout client 2h
use_backend example_backend if { ssl_fc_sni example_backend }

backend example_backend
mode http
timeout connect 5m
timeout client 5m
server example.com example_server1:10002 check

our problem is
if i strike multiple requests like this
curl --location --request GET ‘https://example.com/health
in single second

then i get the results BUT haproxy close connection with TCP RST (not TCP FIN)
there are no rate limits anywhere in path

if i strike 1 request once a time (i.e. 5 seconds)
then connection is closed with TCP FIN

it’s very similar problem reported here Why is HAProxy often sending TCP RESETs instead of FINs to close connections to its backend nodes? (#10589) · Issues · GitLab.com / GitLab Infrastructure Team / infrastructure · GitLab

sw versions
Debian9 + haproxy 1.7(distro)
Debian11 + haproxy 2.2.9(distro)

any ideas where to dig?