The question is ether unlimited in supply?
Actually, this "limited supply" of bitcoin was one of its biggest mistakes if ever bitcoin intended to become a currency (which it isn't going to be). But it was a brilliant marketing gimmick.
First of all, "limited supply ever" is a silly notion, because nobody cares what will happen when the Sun will swallow the earth 1 billion years from now. So we can say that whatever we do, all of our plans are going to be limited to at most 1 billion years.
Well, within 1 billion years, a coin with tail emission such as ethereum will also have a "finite supply".
The belief that it matters whether after 1 billion years, there will still be coins emitted or not, is ridiculous, I hope you agree. Now, consider a coin that emits a constant block reward for "the first billion years, and then stops emitting rewards". Strictly speaking, that is a coin with limited supply, like bitcoin. Only bitcoin does it over 140 years, and this coin, over 1 billion years, but in principle, both are coins with limited supply.
Now, consider another coin, that has the same emission as the first one, but doesn't stop after 1 billion years. This is an "evil coin with unlimited supply" because it will emit still coins at 3 billion years, while the first one, and bitcoin, both stopped.
There's honestly no difference between both: their emission schemes are identical for the first billion years, and after that, none will exist.
Bitcoin has been emitting new coins ever since it got in existence, and most probably, bitcoin will disappear before 140 years. So bitcoin will also be a coin with "unlimited supply during its life time".
But the fundamental reasons why this decreasing supply is problematic are the following:
1) "unlimited seigniorage". The early adopters got their masses of coins, which were easily produced, for very low costs, and will, as time goes by, be able to spend them to obtain more and more value. Being able to make money at a much lower cost than it represents afterwards, is exactly what seigniorage is about. So these early adopters are the equivalent of central bankers printing money almost for free, and being able to buy a lot of stuff with it. In fact, the emission curve of most coins, like bitcoin, is inverse to what it should be. Ideally, the emission curve should follow adoption: in the beginning, almost no coins, and then, as adoption increases, emitting more and more coins, so that a price stability follows, and all participants have similar seigniorage (which they burn with PoW).
2) deflationary spiral and hoarding. An asset that is rare and of decreasing supply, takes on value in many cases. As such, one has no reasons to spend these coins, but rather to hoard (hodl) them. But then, they are not used as a currency. You'd be crazy to pay someone with a coin today against value X, if you know that that coin will be worth 2X tomorrow. You keep your coin, and you pay the guy with some less valuable asset like fiat. So nobody is really interested in using bitcoin as a currency, but wants to buy it mainly to hodl and "invest".