It's relatively left but not far-left, and it hasn't really moved much in decades, though the rapid movement of the right end of the Overton Window over the past couple decades (and particularly the past few years) may make it seemed to have moved left to those whose perceptions are driven by distance from the center of their own identity group, and identify with a right-leaning (either conservative or right-libertarian) faction.

Sure, but I could say the same with much of the South and conservatism.

Judging by the hordes of homeless people I seriously doubt that SF has a far left ideology

It's also entirely unnecessary to guess at this.

We have voting records and financial contributions to campaigns. Both tell the same exact story. San Francisco is as far left as cities get in the US.

The mistake being made by the top level parent, is thinking that there was ever actually a wide-spread libertarian burst. There was not. That was nothing more than a media meme for a few minutes, mostly thanks to Andreessen, Thiel and a few others. SF overall has been extreme left for the last 40 years plus.

Marc Andreessen for one, has entirely disappeared from the public discussion politically. He's a particularly openly avowed libertarian type in terms of beliefs. There's a reason he shut down like he did, it's the same reason Thiel is being evicted from the inner circles of tech. There is no room for mistakes in the current police state of speech that exists in SV. One mistake, stepping out of line with dogma, and you're done. Andreessen wants to stay in Silicon Valley and wants to maintain his VC firm at the top tier, so he shut his mouth to put it simply. Thiel is unwilling to go along with the political & speech requirements of continuing to exist in SV.