For those guys looking to do 90-day reporting here at Chiang Mai immigration on 22 July, you MUST use the drive through. Yes, you can walk through it.
This is because those services are moving to the Promenada location. To my knowledge, the 90-day window at the main office by the airport will remain open for vehicles only after tomorrow.
Not sure if volunteers will be at the Promenada location or not.
TLDR : Answer Summary
For 90-day reporting in Chiang Mai as of July 22, you must utilize the drive-through service at the immigration office due to services moving to the Promenada location. Walking through is permitted, but the main office will only serve vehicles moving forward. There is uncertainty regarding the presence of volunteers at the new Promenada location.