A GAO report on NASA's ongoing projects can be found here. On page 70 while discussing the Lucy mission, it says
the ... main engine was the same model used on a series of environmental satellites that have had engine performance problems. The engine has failed in flight more than once and was a single point failure for the Lucy project. As a result, the project completed an engine trade study in July 2017 and decided to select a different engine.
What were the "series of environmental satellites" the report is referring to, and what was the engine?