Another question, is the transaction fee directly proportional to the amount of bitcoin you are sending? I just noticed that this tx is transferring a large sum of bitcoin and yet also had a large amount of fee.
No, it's not as easy as the fee being proportional to the amount you're spending. You could send 100k BTC with a very, very small fee as long as your wallet history isn't too complex. Long story short, the fees are proportional not to the amount of BTC you send but to the weight of the transaction you're sending.
The weight gets lower or higher depending on multiple factors - for example, as far as I can see, the pizza guy received his money from 131 inputs. If there was only 1 input instead of 131, there would've been a much lower tx fee than 0.99BTC.
If you have ever visited
Bitcoin Fees or made a transaction with custom fees, you might've noticed that you could sometimes input a number of satoshis/byte. That is basically choosing how much you want to pay in BTC fees for each byte of your tx's
weight.
Now let's say I gave you 1 BTC and you split it into exactly 1k addresses on a fresh new Electrum wallet, so in the end you'd have 1000 addresses worth 0.001 BTC each. If you ever wanted to spend the 1 BTC I gave you, you'd have to use 1k inputs and that'd turn into a
huge fee in the end.
Back when I used faucets, I had about 10k satoshis entering my wallet every now and then. After about an year of accumulating, I wanted to move everything to another wallet. Well, guess what happened! I had around $15k worth of BTC but there were so many inputs that the automated fee calculus told me I had to pay $10 in fees. I ended up sending it with a 0 sat/byte fee and it took a few months to be confirmed.