Do actually exist a website, page (even a section in Bscscan, Etherscan) where I can track the supply of a certain token and figure out how it changed during the existence of the token?
I mean like the "historical data" section in Coinmarketcap.
We can see smart contracts from tokens, through smart contracts we can see various information related to tokens, be it total supply, market prices, holders, exchanges, and etc
If the information about their smart contract is not available, you can ask the team, but if the token is already available on Coinmarketcap or another tracking site, you can view the smart contract there.