COBS (Comet OBSveration database) contributions indicates that C/2021 Leonard had a significant outburst just prior to its recovery in the evening sky on December 15/16 2021. The comet flared to mag 3.5 and then quickly subsided to mag 5 by December 18.

These three images were captured with a Vixen VSD 100 mm telescope and a Nikon Z7II camera mounted on a Vixen SXP

About 2.5 minutes of images were acquired with subs and stacked with AstroPixelProcessor and finished with Photoshop. With clouds and haze in Tucson and Comet Leonard gaining altitude each day the differences shown are not normalized and are a qualitative product of the captures.