ahhh I see what you mean.
your thoughts on spacing out your connections & isolating is smart. unfortunately if you connect from the same device & browser any government agency or dedicated company with a big enough dataset (google, meta, etc.) would still be able to link you regardless of you IP by browser fingerprint alone. this does make YouTube more specifically being linked to your exact browser fingerprint porblamatic in a high stakes situation. As it, as you said is linked to your identity.
for lower level tracking changing IP regularly is effective. however, instead of switching to your local IP it would be more privacy conscious to just switch to a different VPN server.
unfortunately if you are genuinely worried about government level surveillance or the likes u enter into territory where VPNs often no longer cut it (or at least can't truly be trusted too) as they are centralized & can be forced to make exceptions for law enforcement. traffic analysis is also easier, which makes time correlation deanonimization a more realistic risk when talking about government agencies specifically.
the tor + vpn debate is one that lots of people argue & is excedingly complicated. tor is generally more than enough, unless you are wanted by INTERPOL haha. if you are genuinely worried about suppressive government or world powers targeting you look further into tor, & do not connect directly to your ISP at all as that data is essentially up for grabs to local authorities (depending on locale).
for you specifically I would consider doing your more sensitive tasks in the tor browser without the VPN & then having your normal browser always on the VPN so they would be more difficult to correlate. anything torrent related is low enough stakes that I would imagine just about any proxy would suffice. hope this was helpful ๐.
while I am by no means an expert on this, my gut tells me that this is probably something to do with "nessecary" cookies vs advertising & tracking cookies. its a common loophole for other policies so I wouldnt be surprised if they had some way of circumventing the normal limitations for tracking because of "fraud protection" or the likes.
looking at the cookie descriptors, all of the 1825 day cookies are used to "store &/or access information on device refreshes". the shorter cookies are the only ones that also mention "measuring advertising & content performance".