I can confirm that rebuilding kwin fixes the issue.
It still looks like an unwanted ABI transition…
Here’s the symbols diff for the record :
diff --git a/debian/libwayland-client0.symbols b/debian/libwayland-client0.symbols
index c0d64c6..5ec470c 100644
--- a/debian/libwayland-client0.symbols
+++ b/debian/libwayland-client0.symbols
@@ -15,6 +15,7 @@ libwayland-client.so.0 libwayland-client0 #MINVER#
wl_display_connect@Base 1.0.2
wl_display_connect_to_fd@Base 1.0.2
wl_display_create_queue@Base 1.0.2
+ wl_display_create_queue_with_name@Base 1.23.0
wl_display_disconnect@Base 1.0.2
wl_display_dispatch@Base 1.0.2
wl_display_dispatch_pending@Base 1.0.2
@@ -30,7 +31,9 @@ libwayland-client.so.0 libwayland-client0 #MINVER#
wl_display_read_events@Base 1.2.0
wl_display_roundtrip@Base 1.0.2
wl_display_roundtrip_queue@Base 1.5.91
+ wl_display_set_max_buffer_size@Base 1.23.0
wl_event_queue_destroy@Base 1.0.2
+ wl_event_queue_get_name@Base 1.23.0
wl_keyboard_interface@Base 1.0.2
wl_list_empty@Base 1.0.2
wl_list_init@Base 1.0.2
@@ -47,8 +50,10 @@ libwayland-client.so.0 libwayland-client0 #MINVER#
wl_proxy_create_wrapper@Base 1.11.0
wl_proxy_destroy@Base 1.0.2
wl_proxy_get_class@Base 1.1.0
+ wl_proxy_get_display@Base 1.23.0
wl_proxy_get_id@Base 1.0.2
wl_proxy_get_listener@Base 1.3.0
+ wl_proxy_get_queue@Base 1.23.0
wl_proxy_get_tag@Base 1.17.93
wl_proxy_get_user_data@Base 1.0.2
wl_proxy_get_version@Base 1.9.91
diff --git a/debian/libwayland-server0.symbols b/debian/libwayland-server0.symbols
index 6872566..02730ab 100644
--- a/debian/libwayland-server0.symbols
+++ b/debian/libwayland-server0.symbols
@@ -23,9 +23,12 @@ libwayland-server.so.0 libwayland-server0 #MINVER#
wl_client_get_fd@Base 1.9.91
wl_client_get_link@Base 1.11.91
wl_client_get_object@Base 1.0.2
+ wl_client_get_user_data@Base 1.23.0
wl_client_new_object@Base 1.0.2
wl_client_post_implementation_error@Base 1.17.0
wl_client_post_no_memory@Base 1.2.0
+ wl_client_set_max_buffer_size@Base 1.23.0
+ wl_client_set_user_data@Base 1.23.0
wl_compositor_interface@Base 1.0.2
wl_data_device_interface@Base 1.0.2
wl_data_device_manager_interface@Base 1.0.2
@@ -52,6 +55,7 @@ libwayland-server.so.0 libwayland-server0 #MINVER#
wl_display_next_serial@Base 1.0.2
wl_display_remove_global@Base 1.0.2
wl_display_run@Base 1.0.2
+ wl_display_set_default_max_buffer_size@Base 1.23.0
wl_display_set_global_filter@Base 1.13.0
wl_display_terminate@Base 1.0.2
wl_event_loop_add_destroy_listener@Base 1.0.4