haproxy SSL não funciona, alega 'nenhum algoritmo de assinatura adequado'

Estou configurando o haproxy para atuar como intermediário entre a internet e vários serviços executados em um cluster k8s isolado.

Já testei com sucesso a conexão com o backend via http simples, mas agora estou tentando manipular o componente SSL lá também e, por algum motivo, não importa o que eu tente, estou recebendo o seguinte nos logs:

Jan 22 11:10:22 jake haproxy[170526]: 95.214.55.185:34832 [22/Jan/2025:11:10:21.968] xanadu-ingress-front/3: SSL handshake failure (error:0A000076:SSL routines::no suitable signature algorithm)

Tentar solucionar problemas via openssl s_clientme dá o seguinte (endereços IP e nomes DNS alterados para proteger o culpado):

shadur@luminosity:~$ openssl s_client --connect teapot.example.com:443 
Connecting to 1.2.3.4 CONNECTED(00000003)
40E7B2BBBA7F0000:error:0A000410:SSL routines:ssl3_read_bytes:ssl/tls alert handshake failure:../ssl/record/rec_layer_s3.c:907:SSL alert number 40
---
no peer certificate available
---
No client certificate CA names sent
---
SSL handshake has read 7 bytes and written 335 bytes
Verification: OK
---
New, (NONE), Cipher is (NONE)
This TLS version forbids renegotiation.
Compression: NONE
Expansion: NONE
No ALPN negotiated
Early data was not sent
Verify return code: 0 (ok)

arquivo de configuração do haproxy abaixo:

global
        log /dev/log    local0
        log /dev/log    local1 notice
        chroot /var/lib/haproxy
        stats socket /run/haproxy/admin.sock mode 660 level admin
        stats timeout 30s
        user haproxy
        group haproxy
        daemon

        # Default SSL material locations
        ca-base /etc/ssl/certs
        crt-base /etc/ssl/private


        # generated 2025-01-22, Mozilla Guideline v5.7, HAProxy 3.1.2, OpenSSL 3.4.0, intermediate config
        # https://ssl-config.mozilla.org/#server=haproxy&version=3.1.2&config=intermediate&openssl=3.4.0&guideline=5.7
        # intermediate configuration
        ssl-default-bind-curves X25519:prime256v1:secp384r1
        ssl-default-bind-ciphers ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:DHE-RSA-CHACHA20-POLY1305
        ssl-default-bind-ciphersuites TLS_AES_128_GCM_SHA256:TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256
        ssl-default-bind-options prefer-client-ciphers ssl-min-ver TLSv1.2 no-tls-tickets

        ssl-default-server-curves X25519:prime256v1:secp384r1
        ssl-default-server-ciphers ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:DHE-RSA-CHACHA20-POLY1305
        ssl-default-server-ciphersuites TLS_AES_128_GCM_SHA256:TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256
        ssl-default-server-options ssl-min-ver TLSv1.2 no-tls-tickets

        # curl https://ssl-config.mozilla.org/ffdhe2048.txt > /path/to/dhparam
        ssl-dh-param-file /etc/ssl/private/dhparam


defaults
        log     global
        mode    http
        option  httplog
        option  dontlognull
        timeout connect 5000
        timeout client  50000
        timeout server  50000
        errorfile 400 /etc/haproxy/errors/400.http
        errorfile 403 /etc/haproxy/errors/403.http
        errorfile 408 /etc/haproxy/errors/408.http
        errorfile 500 /etc/haproxy/errors/500.http
        errorfile 502 /etc/haproxy/errors/502.http
        errorfile 503 /etc/haproxy/errors/503.http
        errorfile 504 /etc/haproxy/errors/504.http

crt-store company
  crt-base /etc/ssl/certs/
  key-base /etc/ssl/private/
  load crt "company.com-full.pem" key "company.nl.key" alias "company"
  load crt "company.net-full.pem" key "company.net.key" alias "company.net"

frontend xanadu-ingress-front
  bind 1.2.3.4:80
  bind 1:2:3:4:5:6:7:8:80 transparent
  bind 1.2.3.4:443 ssl crt-list /etc/ssl/crt-lists/company.list alpn h2,http/1.1
  http-request redirect scheme https unless { ssl_fc }
  default_backend xanadu-ingress-back
  option httplog

backend xanadu-ingress-back
  mode http
  server xanadu 172.16.41.80:80 check

Tenho quase certeza de que estou esquecendo de algo muito simples e óbvio, mas não consigo descobrir o que é. Qualquer ajuda seria apreciada.