After I upgraded Jenkins from a previous LTS to 2.414.1, it shows two instances of "Build Queue" in the left sidebar:

• "Build Queue" above "Build Executor Status" is the usual Jenkins widget that does not have the queue manipulation buttons.
• "Build Queue" below "Build Executor Status" is the widget from simple-queue-plugin.

The Jenkins log shows:

elok. 24, 2023 5:47:26 IP. WARNING cz.mendelu.xotradov.SimpleQueueInit postInitialize

SimpleQueuePlugin unable to remove default widget, reason: not normal widget setup

That warning comes from https://github.com/jenkinsci/simple-queue-plugin/blob/simple-queue-1.4.3/src/main/java/cz/mendelu/xotradov/SimpleQueueInit.java.