I suspect they are A/B testing it. A relative’s computer I help maintain did not replace Firefox as a default, but it did replace a PDF reader default (SumatraP

I suspect they are A/B testing it. A relative’s computer I help maintain did not replace Firefox as a default, but it did replace a PDF reader default (SumatraPDF iirc) with Edge, and on the next PDF double click - when Edge opened - it did a bunch of other things like logging in to Microsoft.