Mypal
Mypal is a discontinued fork of Moonchild Productions' Pale Moon browser, targeted primarily at Windows XP. It was developed by Feodor2.
The latest and final version was 29.3.0 based on the respective version of Pale Moon. Like all browsers based on UXP, it uses the Goanna rendering engine, a fork of Gecko.
Mypal is no longer in development. It has been replaced by Mypal 68 which is considered a separate browser.
Use on CollabVM
Mypal was the default browser on VM2, from March 2021 to April 25th 2022, when it was replaced with Mypal 68. Previously, VM2 used Firefox 52 ESR as the default browser, and before that, Google Chrome.
Discontinuation
Due to the Pale Moon developers disliking the creation of forks for the use on Windows XP, and older operating systems in general, they decided all of a sudden that the browser was no longer in line with the MPL (Mozilla Public License), and therefore created a GitHub issue to complain about it. Many things happened, but Feodor was essentially bullied into discontinuing the browser. The final version can still downloaded from its website.