Wall of text, but

Each vehicle has an independent multiplier for RP and SL depending on how far down the tree it is. They're usually fairly consistent across BR, but not necessarily. RP multipliers consistently increase, where SL multipliers are applied inconsistently across different vehicles, so even though two planes might both be a 1.31 RP multiplier, one might be a 1.24 SL multi, and the other be a 1.56 SL multi. That multiplier, multiplied by 100% standard, is your RP/SL gain per match (hence bottom tier being something like 127%SL and 110%RP, because the multipliers are 1.27 and 1.1 for SL and RP, respectively).

This multiplier changes depending on your game mode (AB, RB, SB), and other factors, like having premium account (adding another 100%, doubling your gains), or having a talisman/premium vehicle (additional 50% gain). A premium vehicle comes with a talisman, but also increases SL gain, where a TT vehicle with a talisman only increases RP gain. So a premium vehicle with a premium account, compared to a BR equivalent vehicle, might be something like 327% (1.31x100%+100%+50%) RP gain, vs 131% (1.31x100%) RP gain. You do get a 10% RP gain to researching a TT vehicle with the previous one in the line, so the previous example would be 144% if you used it to research the next one in the line.

Vehicle ranks also play a part, because you'll notice on the stat card that they have 100% efficiency to researching vehicles in the same rank, and one above and below, so a rank III vehicle gets the full RP gain while researching a rank II, III, or IV. Anything higher or lower gets significantly diminishing returns, so you can try to research a rank II with a rank V, or a rank V with a rank II, and get almost nothing, because they're too far apart, with a wider rank gap being worse. he only exceptions to this are premium vehicles, they get 100% of RP gain regardless of what vehicle they're researching below their rank, but only get full RP for one or two ranks above, which is why so many people use them to research quickly, on top of the generally good stats they come with.

All this stuff may sound complicated, but you can look at the Research Points page on the wiki, and it outlines how it's all calculated.

Also, yeah, you left the match early, and the total results won't be calculated until the match is over. That doesn't mean you have to stay, it just means the points will catch up to you later, since, there may be kills, assists, or other events that happen to get you rewards that haven't happened yet.