lotta variables, but the latest I’ve read is that quicktime and chrome use gamma 1.96 and VLC uses gamma 2.2.
sometimes you can set VLC to use openGL then it changes the drivers it uses. quicktime has atom tags you can edit to force color profiles.
Each browser sees a different color although you can force some of them to use color management.
your video card has video legal or full range settings if its a nvidia card in its control settings.
You proofed all this yourself when you imported it back into AE. AE will pass through what your monitor sees. If you enable it’s display management, it will use your monitor’s color profile.
Furthermore, most macs use P3 not sRGB for their color profile. They also use Trutone which you have to disable so they don’t autowhite balance. The internet uses sRGB so there may be an issue there as well if the playback software doesn’t account for that.
Youtube will usually use the cheap colors codec h.264. you can click edit, then ‘retouch’ to get it to re-encode to the better VP9 codec colors.
Vimeo will sometimes use video range not full range, especially if you use certain Prores flavors.
Finally, there is no good answer because there is no standard as each OS, site, browser, player, has their own flavor of what is right. All you can do is recommend a viewing ‘plan’ that you’ve tested that works.