After a ride, LeCoach can append its analysis to the activity description in Intervals.icu — and if you have Intervals.icu and Strava linked, that description also appears on Strava.
There are two separate toggles, both in Settings → Appearance → 'Add LeCoach analysis to activity description':
Workout execution score — appends the score summary (score, duration, intensity, load and zone match) to the description. On by default.
AI analysis summary — appends the AI-written analysis of your ride. Off by default.
Turn either toggle off to stop LeCoach from writing that part to your activity descriptions in Intervals.icu (and therefore Strava).
Note: this controls the activity description. The 'by LeCoach App' suffix on planned workout names is a separate setting in Settings → Workout Settings — see Renaming workouts and the 'by LeCoach App' label.