How can Dollar be strong when it has constant inflation. It was nearly so out of control with awful inflation recently they've had to quadruple the interest payable including on the national debt which is the real spiral of a plughole we're going to plunge down eventually.
The USD is stronger, which means people are comparing it to other currencies, comparing the US economy to other countries, no one is comparing it to scarce assets like gold, silver or bitcoin and think that the USD is stronger.
That constant loss of value is undeniable and at this point some say unavoidable ie. Dollar is certain to collapse. I dont presume that much myself because the country itself is strong but its the most rational conclusion; we have a bias to believe things last forever, misplaced patriotism etc. Loyalty to governmental policy which doesnt pay its bills and eventually cant pay its bills will end up unfortunate as misaligned judgement but its more controversial to say so then pretend its fine.
Ignoring the rotten core, just on face value Dollar index has risen and sustained above 100. We can label this strong but its relative to other FIAT currencies who ironically wish only to stay relative to the global reserve currency and maintain trading relationships.
The USD will collapse when the US economy collapses and this is very unlikely but it is certain that the USD will be replaced by another currency and another economy will replace the US economy will happen. Nothing lasts forever and American dominance is no exception but it will probably take us a little longer and it won't happen anytime soon.