Remember that TikTok is full of influencers who jump on bandwagons, and the big companies give out car seats like sweets to influencers because they want other people to buy them.
Similarly, the facebook groups end up echo chambers where everyone just repeats what everyone else says even if they have no experience of any of the seats. And they are usually run by retailers. I do think some of the retailers are in it to spread awareness and give genuine advice about ERF, I'm not disputing that they exist at all. But you've got to see through the fact that for some, it will be about money and they are likely to nudge the group consensus towards pricier seats, because it suits their business model. And retailers also get visited by brand reps all the time who will push the top line models and not so much the cheaper ones, so they may not have a totally objective view either.
The Pixel Pro is a nice seat, but the Cosmo is very similar and much cheaper.
With infant carriers you don't get a direct correlation between price and safety, so the idea of "putting a price on baby's safety" doesn't make sense in this case. There is actually very little difference in safety terms between the cheap/basic infant carriers and the high end, all singing all dancing ones. For example, Joie i-Snug, Cybex Aton B, Graco SnugEssentials, Maxi Cosi Cabriofix i-size, these seats are all about £100 or less, and the bases priced similarly, yet they get safety ratings equivalent or better than seats like Maxi Cosi Pebble 360 Pro, Britax Babysafe 5Z2, Cybex Cloud T, Nuna Arra Next - which are all top of the line with prices to match (Over £400 for any of these base + car seat sets).
It makes a bit more sense in the context of the next stage seats because you do get a progression in safety from the £25-60 supermarket seats > £80-150 cheapy seats > £200-300 ERF, Swedish Plus Tested seats.
But again the comparison then stops there. You can find ERF car seats on the market going right up to £600+ but they aren't any safer than any other Swedish plus tested seat.
I think there's an issue there in that £200 (and especially £300, if there aren't any good offers) is a lot of money to a lot of people, especially if you're comparing it to under £50. I don't actually agree with the way that the FB groups approach this, because I think a lot of the time, it amounts to bullying. But there is an aspect of cost mattering when it comes to second stage car seats. Whereas you just don't even really have the extremely budget/basic/flimsy seats on the market in the infant carrier section (at least at the moment) - Joie Juva tends to be the cheapest at about £65.