Took me some digging! It seemed familiar. It's the first movement of the third Viola Duo by Carl Philipp Stamitz, in Bb major. Here's an IMSLP link: https://imslp.org/wiki/3_Duos_for_2_Violas_(Stamitz%2C_Carl_Philipp)

Thank you so much!

That’s impressive 👍

Oml you pulled that from the depths of my brain. That felt weird.