Tx. The Intervals.icu load for that run has been calculated from the HR data using HRSS and the number looks “good” (103 for a 1h17 run is 88% intensity which is reasonable). This is designed to produce numbers similar to what you might get from power data for the same activity (TSS formula). In general a 1hr max effort should get you load of about 100.
I don’t know how Strava and Garmin calculate their numbers (165 and 162). They is clearly not on the same scale as TSS.
Intervals.icu tries to get everything on the same load scale for power so activities without power are comparable to those with power.