At my last large tech company we moved from Phabricator to JIRA. It was a global downgrade for actual users through and through. Engineering hated it, usage of ticket tracking went down a lot because nobody wanted to interact with that crappy tool. A good chunk of team's tasks just went into more informal google docs, sheets & slack channel bots as a result and the teams responsible for managing the tool had a hard time getting real adoption.

We were forced to get off of Phabricator because it was abandoned, but JIRA was still a downgrade in every way. Linear will eat JIRAs lunch and in a decade, it's going to go the way of HipChat as the thing that everyone used but nobody talks about.