You're likely thinking of Yuzu which was a switch emulator. Nintendo probably targeted them because they were about to launch the switch 2 and wanted to send a message.

It being a Switch emulator certainly didn't help. However, the primary reason Nintendo went after Yuzu was that Yuzu devs were openly accepting payment for special updates to run Tears of the Kingdom. TOTK was, at the time, only available because of a leak and had not officially released.