As i know we have unofficial api endpoint use to retrieve all the following-site with O365 sites included:
https://mytenant.sharepoint.com/_vti_bin/homeapi.ashx/sites/followed?mostRecentFirst=true&start=0&co...
Recently it has stop working (happened in some tenant).
The api return empty data

but Sharepoint still working fine with this api (https://westeurope3-sphomep.svc.ms/api/v1/sites/followed?mostRecentFirst=true&start=0&count=100&fill...)

Did microsoft make any change in the "vti_bin/homeapi.ashx" api?
Can some help me at this matter.
I'm really appreciate it.