Entry light switch controls adjacent bedroom lighting
@Ed Beal @NoSparksPlease - so yes, these 2 wires needed to be wire nutted together, leaving only the red connected. That resolved the issue, and i've found this video to explain what was happening https://www.youtube.com/watch?v=wRSgemIxamU (Scenario 2 at the 2:47 mark)
@manassehkatz-Moving 2 Codidact 2 - yes the diagram is showing the light box, not the switch box
@ThreePhaseEel - I will indeed post pictures if this ever happens again -- assuming I can't get a hold of an electrician as the first option.
Thanks for the feedback everyone!