The only thing that leaves me confused is that BTC is legal tender in El Salvador, and the blueprint of the law defines selling as "changing into a legal tender".
So maybe BTC is an exception to the rule and "taxically" untouchable?
... or maybe the lawmaker could argue when you
buy bitcoin or swap some shitcoin for bitcoin, you're also "cashing out" the (crypto)currency into a legal tender - so you owe CGT.
You never know what byzantine concepts the lawmakers are going to come up with.
Lawmaker could easily argue you owe them BTC tax, if you make BTC profits from alts. The only reason in other countries that BTC based profits are not taxed is because they don't accept Bitcoin as currency. In summary, you can't send them profits that they don't or can't accept. El Salvador have taken a different role it seems, they accept your Bitcoin profits from altcoins I image, and will probably expect it as well.
This is probably one of the only downsides of a nation accepting Bitcoin as currency, having to send them BTC from altcoin profits... it also sounds like a small price to pay in the long-term.
However does this mean you don't owe tax from fiat currency profits, if you return it to the nation's currency? It's confusing

It sounds to me like you have a preoccupation with shitcoins. Your previous voluminous post about falling bitcoin dominance being likely to prevent further BTC v fiat gains; a chart to try to show some similar point; and now trying to argue that a downside of El Salvador's pioneering move to accept bitcoin as legal tender is that you might have to pay tax on profits from shitcoins.
As I said, I was theorising that shitcoin profits might have to be paid in Bitcoin - and that it's a small price to pay. You realise this would make it less of an incentive to invest in shitcoins right?
Otherwise the recent correctionsd in Bitcoin dominance has decreased fiat values, this is fact not opinion. The chart really doesn't show that, but for those who are more in tune with BTC's price movements in relation to it's dominance, have probably noticed the correlation by now, as it's the inverse of the previous altcoin season, DYOR. I understand that facts can be hard to hear or read, but it still doesn't make it an opinion I'm afraid.
Do you have some heavy bags of shitcoins, by any chance?
If you are paying attention, quite obvious not. Since 40% dominance, I've taken the majority of my shitcoin profits from a 10% trading account. Previously my holdings were 60% with Ethereum (for statistical reasons, not fundmental) in order to return 80% profit on Bitcoin from 0.04. Bingo. I've otherwise happily put X amount of BTC into shitcoins, returned X.2 amount profits and still hold X.1 amount, excluding the big move in Ethereum that earned me insane amount of sats. So obviously no complaints so far, apart from maximalists obviously. I play the cycles, 60% dominance down to 40% specifically, and now I see 40% moving back to 50%-60%. Before waiting for the next move for more sats, likely down to 30%. I play statistics, not emotions I'm afraid.
So yes I've lived off shitcoins this year, those that have outperformed BTC and have no regrets. I'm acknowledging it might an issue in the broader sense however, one I don't advocate, it's just a way to earn a living. I get that some people here have to earn a fiat living to survive, but others here earn a satoshi living instead. It's controvsersial I get that, but please but your jealously, envy or resentment aside for a second and understand my original point...