What does pio --version return from the CLI?
I think also the same was observed at Error: You are not connected to the Internet - pio 3.6.7 and Cannot install platform espressif32 on docker ubuntu:rolling. PIO 4.3.4-1 - #18 by ivankravets where the answer is basically: Upgrade to the latest core, the projects are backwards compatible. I think it also has something to do that file hosters were shut down that the old software relied on (bintray…), which is much better today with a content distribution network.
Of course for your installation there’s the caveat of getting a newer Python to be able to run PlatformIO at all. But to my knowledge, when installing it in VSCode for example, it does so with a portable Python version in a Python virtual environment, so the machine’s Python version shouldn’t matter too much (except being able to execute the installer).
Maybe @ivankravets has additional thoughts on this.