Retiring the Mozilla Location Service · Issue #2065 · mozilla/ichnaea
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The accuracy of Mozilla Location Service (MLS) has steadily declined. With no plans to restart the stumbler program or increase investments to MLS we have made the decision to retire the service. I...

Patent infringement threat(Skyhook Holdings, Inc), lack of further investment seems to have been the reason of killing the service around 2021. It seems google location service seems to be the only player in town(other than OpenCellID, which I do not have experience with).