IDE downgrades and upgrades PIO core

If I issue any build-related command in IDE (build, clean, upload), the core gets updated to 3.4.0a6 but then when I call serial monitor (still from within IDE), core gets downgraded to 3.3.0. Is there any way to pin core version so it does not do this dance? I have “use built in PIO core” set and I would like to still have it this way.

IDE: 2.0.0-beta.2
core: 3.4.0a6 (default)

Update: upload spiffs task (for ESP8266) downgrades core too.

It looks that you have multiple versions of PIO Core in a system. Please uninstall other Cores.

which pio
pip uninstall platformio

P.S: Please keep PIO IDE’s Core. You can install it globally into a system (Menu: PIO > Install Shell Commands)

Thanks, I did not have problems with this to date.