You can keep specific versions of boards (like ESP8266 v2.7.4) that you know are compatible with an old project, without affecting your main computer. Zero Footprint:

: Arduino IDE 2 introduces advanced debugging capabilities. With features like breakpoints, variable inspection, and real-time expression evaluation, developers can now more easily identify and fix issues in their code.

Now that portable mode is active, everything is self-contained within that portable folder. If you open the portable folder, you will see new subdirectories automatically generated:

While portability offers freedom, it comes with a performance cost. Running an IDE and compiling code from a cheap, slow USB 2.0 drive will result in significantly longer compile times. For the best experience, use a USB 3.1 flash drive external SSD

If a library breaks your code, delete the corrupted portable folder and unzip the backup.