Maybe the proper way to go would be to remove DNS4all entries in /usr/share/yunohost/conf/dnsmasq/plain/resolv.dnsmasq.con:
# diff -Naur /usr/share/yunohost/conf/dnsmasq/plain/resolv.dnsmasq.conf.orig /usr/share/yunohost/conf/dnsmasq/plain/resolv.dnsmasq.conf
--- /usr/share/yunohost/conf/dnsmasq/plain/resolv.dnsmasq.conf.orig 2025-10-20 12:50:12.089230400 +0200
+++ /usr/share/yunohost/conf/dnsmasq/plain/resolv.dnsmasq.conf 2025-10-20 12:50:20.657384672 +0200
@@ -24,6 +24,3 @@
nameserver 2001:1608:10:25::1c04:b12f
nameserver 84.200.70.40
nameserver 2001:1608:10:25::9249:d69b
-# DNS4all
-nameserver 194.0.5.3
-nameserver 2001:678:8::3
and yunohost tools regen-conf dnsmasq -f ?