I’ve just updated from 2.3.3 to 2.4.1 on Linux Mint 19.3 using Panda Jim’s PPA and noticed a couple of issues regarding effects.
The enabled state of plugins doesn’t seem to be preserved with existing Audacity data settings. Many plugins adopt a disabled state. Starting with a fresh data settings folder produces a different result.
In 2.4.1 from the PPA, the Limiter plugin isn’t present. It’s not listed in the Add/Remove plugins tool.
UPDATE: This may be related to this thread - https://forum.audacityteam.org/t/can-no-longer-enable-plugins-after-2-3-3-2-4-0-update/57039/1