I think they have the web play question in their FAQ somewhere and it does include as a download. There’s no real way to know how their telemetry is calculating this though.
A: Games on all platforms are eligible for the fee but will only incur costs if both the install and revenue thresholds are crossed. Installs - which involves initialization of the runtime on a client device - are counted on all platforms the same way (WebGL and streaming included
I think they have the web play question in their FAQ somewhere and it does include as a download. There’s no real way to know how their telemetry is calculating this though.
https://forum.unity.com/threads/unity-plan-pricing-and-packaging-updates.1482750/
Wow… I expect that WebGL telemetry to be less reliable than from an installed app. “No cookies found, guess this is a brand new download, chaps!”