A particularly easy suggestion I first heard on the Risky Biz podcast after the reporting about fake CISOs: LinkedIn should prominently display profile creation dates.
https://stripe.com/identity (only as an example, many vendors offering this service)
LinkedIn allows you to change your name and profile content as often as you wish, and doesn't keep or publicly expose any of a profile's past info.
No? I guess not. Funny to imagine though — the numbers of accounts on said platforms would collapse like the birth of a black hole. I'll bet it would be a lot more of a pleasant place to hang out though.