diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index fe16171e38..f6ed33d344 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -147,10 +147,6 @@ stages:
 
 # Debian
 
-.debian-bullseye-amd64: &debian_bullseye_amd64_image
-  image: "$CI_REGISTRY_IMAGE:debian-bullseye-amd64"
-  <<: *linux_amd64
-
 .debian-bookworm-amd64: &debian_bookworm_amd64_image
   image: "$CI_REGISTRY_IMAGE:debian-bookworm-amd64"
   <<: *linux_amd64
@@ -1265,9 +1261,9 @@ unit:clang:asan:
 gcc:tsan:
   variables:
     CC: gcc
-    CFLAGS: "${CFLAGS_COMMON} -Wno-stringop-overread -ggdb -O2 -fsanitize=thread -Wl,-rpath=/usr/local/lib -Wl,--enable-new-dtags"
+    CFLAGS: "${CFLAGS_COMMON} -Wno-stringop-overread -ggdb -O2 -fsanitize=thread"
     LDFLAGS: "-fsanitize=thread"
-    EXTRA_CONFIGURE: "--with-libidn2 --enable-pthread-rwlock --without-jemalloc PKG_CONFIG_PATH=/usr/local/lib/pkgconfig"
+    EXTRA_CONFIGURE: "--with-libidn2 --enable-pthread-rwlock --without-jemalloc PKG_CONFIG_PATH=/opt/tsan/lib/pkgconfig"
   <<: *tsan_fedora_40_amd64_image
   <<: *build_job
 
@@ -1294,9 +1290,9 @@ clang:tsan:
   <<: *build_job
   variables:
     CC: "${CLANG}"
-    CFLAGS: "${CFLAGS_COMMON} -fsanitize=thread"
+    CFLAGS: "${CFLAGS_COMMON} -ggdb -O2 -fsanitize=thread"
     LDFLAGS: "-fsanitize=thread"
-    EXTRA_CONFIGURE: "--with-libidn2 --enable-pthread-rwlock --without-jemalloc"
+    EXTRA_CONFIGURE: "--with-libidn2 --enable-pthread-rwlock --without-jemalloc PKG_CONFIG_PATH=/opt/tsan/lib/pkgconfig"
 
 system:clang:tsan:
   variables:
@@ -1316,52 +1312,6 @@ unit:clang:tsan:
     - job: clang:tsan
       artifacts: true
 
-# Jobs for Debian 11 "bullseye" (amd64)
-
-clang:bullseye:amd64:
-  variables:
-    CC: ${CLANG}
-    CFLAGS: "${CFLAGS_COMMON} -Wenum-conversion"
-  <<: *debian_bullseye_amd64_image
-  <<: *build_job
-
-system:clang:bullseye:amd64:
-  <<: *debian_bullseye_amd64_image
-  <<: *system_test_job
-  needs:
-    - job: clang:bullseye:amd64
-      artifacts: true
-
-unit:clang:bullseye:amd64:
-  <<: *debian_bullseye_amd64_image
-  <<: *unit_test_job
-  needs:
-    - job: clang:bullseye:amd64
-      artifacts: true
-
-gcc:bullseye:amd64:
-  variables:
-    CC: gcc
-    CFLAGS: "${CFLAGS_COMMON}"
-    # See https://gitlab.isc.org/isc-projects/bind9/-/issues/3444
-    EXTRA_CONFIGURE: "--with-libidn2 --without-jemalloc --disable-leak-detection"
-  <<: *debian_bullseye_amd64_image
-  <<: *build_job
-
-system:gcc:bullseye:amd64:
-  <<: *debian_bullseye_amd64_image
-  <<: *system_test_job
-  needs:
-    - job: gcc:bullseye:amd64
-      artifacts: true
-
-unit:gcc:bullseye:amd64:
-  <<: *debian_bullseye_amd64_image
-  <<: *unit_test_job
-  needs:
-    - job: gcc:bullseye:amd64
-      artifacts: true
-
 # Jobs for Clang builds on Debian 12 "bookworm" (amd64)
 
 clang:bookworm:amd64:
@@ -1623,7 +1573,7 @@ respdiff:tsan:
     CC: gcc
     CFLAGS: "${CFLAGS_COMMON} -Og -fsanitize=thread"
     LDFLAGS: "-fsanitize=thread"
-    EXTRA_CONFIGURE: "--disable-dnsrps --enable-pthread-rwlock --without-jemalloc"
+    EXTRA_CONFIGURE: "--disable-dnsrps --enable-pthread-rwlock --without-jemalloc PKG_CONFIG_PATH=/opt/tsan/lib/pkgconfig"
     MAX_DISAGREEMENTS_PERCENTAGE: "0.5"
     TSAN_OPTIONS: "${TSAN_OPTIONS_DEBIAN}"
   script: