Was Paho ever included in the default pyenv environment installed by PlatformIO o_O? Try checking whether you can still access the pip3 executable for PlatformIO and instruct it to install that library. (Zephyr Blink example build fails after new install - #2 by maxgerhardt)
I’ve also wondered about why that change was made, see PlatformIO IDE 2.0 for VSCode 🚀